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3.10. Removing an Unsuccessfully Demoted
Domain Controller
Problem
You want to manually remove a domain controller from Active Directory if the demo‐
tion process was unsuccessful or you are unable to bring a domain controller back online
after a hardware or software failure.
Solution
Use the following steps to remove a domain controller:
1. Go to the Windows command line and type ntdsutil.
2. From the ntdsutil menu, type metadata cleanup.
3. Type remove selected server cn=<ServerName>,cn=Servers,cn=<SiteName>,
cn=Sites,cn=Configuration,dc=<ForestRootDomain> to remove the server met‐
adata associated with dc1.adatum.com.
If successful, a message will state that the removal was complete. However, if you receive
an error message, check to see if the server’s nTDSDSA object (e.g., cn=NTDSSet
tings,cn=DC5,cn=Servers,cn=MySite1,cn=Sites,cn=Configuration,dc=ada
tum,dc=com) is present. If so, the demotion process may have already removed it, and
it will take time for the change to replicate. If it is still present, try the ntdsutil procedure
again, and if that doesn’t work, manually remove that object and the parent object (e.g.,
cn=DC5) using ADSI Edit or another tool. (Deleting Active Directory objects is discussed
in Recipe 4.24.)
Follow these additional steps to remove all traces of the domain controller:
1. Delete the CNAME record from DNS for <GUID>._msdcs.<RootDomainDNSName>,
where <GUID> is the objectGUID for the server’s nTDSDSA object as obtained via ADSI
Edit or a command-line tool such as AdFind. You’ll need to manually check and
delete any associated SRV records. Delete any A and PTR records that exist for the
server. When using Microsoft DNS, you can use the DNS MMC snap-in to accom‐
plish these tasks.
2. Delete the computer object for the server under ou=DomainControl
lers,<DomainDN>. This can be done using the Active Directory Users and Com‐
puters snap-in or PowerShell. (Deleting objects is described in Chapter 4.)
3. Delete the FRS Member object for the computer contained under cn=DomainSys
temVolume (SYSVOL share),cn=file replication service,cn=sys
tem,<DomainDN>. This can be done using the Active Directory Users and Computers
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snap-in when Advanced Features has been selected from the View menu (so the
System container will be displayed), or with the AdMod tool.
4. Delete the server object associated with the failed domain controller in the Active
Directory Sites and Services MMC.
Discussion
If the domain controller that you are forcibly removing from Active Directory is the
last one in an Active Directory domain, you’ll need to manually remove the domain
from the forest as well. See Recipe 2.5 for more information on removing orphaned
domains.
Here are some additional issues to consider when you forcibly remove a domain
controller:
• Seize any FSMO roles the DC may have had to another domain controller. (Man‐
aging FSMO roles is discussed later in this chapter.)
• If the DC was a global catalog server, ensure there is another global catalog server
configured in the site that can handle the increased workload.
• If the DC was a DNS server, ensure that there is another DNS server that can handle
the additional name resolution queries, and be sure that your clients are configured
to use the correct name server.
• If the DC was the RID FSMO master, check to make sure duplicate SIDs have not
been issued (see Recipe 2.25).
• Check to see if the DC hosted any application partitions, and if so, consider making
another server a replica server for those application partitions (see Recipe 16.8).
If the (former) domain controller that you forcibly removed is still active or otherwise
returns to your network, you should strongly consider reinstalling the operating system
to avoid potential conflicts from the server trying to reinsert itself back into Active
Directory.
See Also
Recipe 2.5 for removing an orphaned domain; Recipe 2.25; Recipe 3.31 for seizing
FSMO roles; Recipe 4.24; Recipe 16.8
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3.11. Renaming a Domain Controller
Problem
You want to rename a domain controller.
Solution
Your first step in renaming a domain controller is as follows, where <NewName> is a fully
qualified domain name (FQDN):
> netdom computername <CurrentName> /Add:<NewName>
The new name will be automatically replicated throughout Active Directory and DNS.
Once you’ve verified that the new name has replicated (which may take some time
depending on your replication topology), you can designate it as the domain controller’s
primary name as follows, and then reboot the domain controller:
> netdom computername <CurrentName> /MakePrimary:<NewName>
See Chapter 12 for information on verifying Active Directory
replication.
Once you’re satisfied that your clients are accessing the domain controller using its new
name, you can remove the old computer name using the following syntax:
> netdom computername <NewName> /remove:<OldName>
Discussion
An option in the netdom utility allows an alternate computer name to be associated with
a computer in Active Directory. Once you’ve added a new name, you can then set that
name to be the primary name, thereby renaming the computer.
The old name effectively remains with the domain controller until you remove it, which
can be done using the netdom computername /Remove:<Name> command. You should
reboot the server before removing the old name. The old names are stored in the msDSAdditionalDnsHostName and msDS-AdditionalSamAccountName attributes on the do‐
main controller’s computer object.
If the domain controller has any version of Microsoft Exchange installed on it, renaming
the domain controller is unsupported.
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3.12. Finding the Domain Controllers for a Domain
Problem
You want to find the domain controllers in a domain.
Solution
Using a graphical user interface
1. Open the Active Directory Users and Computers snap-in (dsa.msc).
2. Right-click on the target domain and select Find.
3. In the Find drop-down box, select Computers.
4. In the Role drop-down box, select Writable Domain Controllers or Read-Only
Domain Controllers.
5. Click Find Now. The list of domain controllers for the domain will be present in
the search results pane.
Using PowerShell
To find all of the domain controllers in the adatum.com domain, use the following
command:
Get-ADDomainController -Filter { domain -eq "adatum.com" } | select Name
Discussion
There are several ways to get a list of domain controllers for a domain. The GUI solution
simply uses the built-in “Find” functionality of the Active Directory Users and Com‐
puters MMC. The PowerShell solution uses a dedicated cmdlet for getting information
about domain controllers.
For yet another solution, see Recipe 3.26 to find out how to query DNS to get the list of
domain controllers for a domain.
See Also
Recipe 3.26 for finding domain controllers via DNS
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3.13. Finding the Closest Domain Controller
Problem
You want to find the closest domain controller for a particular domain.
Solution
Using a command-line interface
The following command finds the closest domain controller in the specified domain
(<DomainDNSName>); that is, a domain controller that is located in the same site or in the
closest site if a local DC is not available. By default, it will return the closest DC for the
computer from which nltest is being run, but you can optionally use the /server option
to target a remote host. If you are interested in finding a DC within a particular site
regardless of whether it is the closest DC to you, you can also optionally specify
the /site option to find a domain controller that belongs to a particular site:
> nltest/dsgetdc:<DomainDNSName> [/site:<SiteName>] [/server:<ClientName>]
Using PowerShell
Get-ADDomainController -Discover
The preceding command will discover the closest domain controller from the computer
where the command is run.
Discussion
The DC locator process defines how clients find the closest domain controller. The
process uses the site topology stored in Active Directory to calculate the site a particular
client is in. After the client site has been identified, it is a matter of finding a domain
controller that is a member of that same site or that is covering for that site.
The Microsoft DsGetDcName Directory Services API method implements the DC Lo‐
cator process, but unfortunately it cannot be used directly from a scripting language,
such as VBScript. The nltest /dsgetdc command is also a wrapper around the
DsGetDcName method, and it is a handy tool when troubleshooting client issues related
to finding an optimal domain controller.
Using a command-line interface
You can use nltest to return the closest domain controller that is serving a particular
function. Some of the available functions include a global catalog server (/GC switch),
time server (/TIMESERV switch), KDC (/KDC switch), and PDC (/PDC switch). Run
nltest /? from a command line for the complete list.
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Using PowerShell
Similar to nltest, you can specify additional criteria for finding a domain controller by
using the -Filter parameter. The following are some of the most used filters:
IsGlobalCatalog
IsReadOnly
Site
Service
3.14. Finding a Domain Controller’s Site
Problem
You need to determine the site of which a domain controller is a member.
Solution
Using a command-line interface
To retrieve the site for a particular DC, use the following command syntax:
> nltest /dsgetsite /server:<DomainControllerName>
The nltest /dsgetsite command is a wrapper around the DsGetSi
teName method.
Using PowerShell
Get-ADDomainController -Server <DomainControllerName> | FL Name,Site
Discussion
Domain controllers are represented in the site topology by a server object and a child
nTDSDSA object. Actually, any type of server can conceivably have a server object; it is
the nTDSDSA object that differentiates domain controllers from other types of servers.
You’ll often see the nTDSDSA object of a domain controller used to refer to that domain
controller elsewhere in Active Directory. For example, the fSMORoleOwner attribute that
represents the FSMO owners contains the distinguished name of the nTDSDSA object of
the domain controller that is holding the role.
Finding a domain controller’s site using a GUI solution is time-consuming but can be
accomplished by using LDP or Active Directory Sites and Services.
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See Also
Recipe 3.13
3.15. Moving a Domain Controller to a Different Site
Problem
You want to move a domain controller to a different site.
Solution
Using a graphical user interface
1. Open the Active Directory Sites and Services snap-in (dssite.msc).
2. In the left pane, expand the site that contains the domain controller.
3. Expand the Servers container.
4. Right-click on the domain controller you want to move and select Move.
5. In the Move Server box, select the site to which the domain controller will be moved
and click OK.
Using a command-line interface
When using DSMove, you must specify the DN of the object you want to move. In this
case, it needs to be the distinguished name of the server object for the domain con‐
troller. The value for the -newparent option is the distinguished name of the Servers
container you want to move the domain controller to:
> dsmove "<ServerDN>" -newparent "<NewServersContainerDN>"
For example, the following command would move dc2 from the Default-First-SiteName site to the Raleigh site:
> dsmove "cn=dc2,cn=servers,cn=Default-First-Site-Name,cn=sites,↵
cn=configuration,cn=adatum,dc=com" -newparent↵
"cn=servers,cn=Raleigh,cn=sites,cn=configuration,cn=adatum,dc=com"
You can also move an object using AdMod, as follows:
> admod -b cn=<ServerName>,cn=servers,cn=<OldSite>,cn=sites,↵
cn=configuration,<ForestRootDN> -move cn=servers,cn=<NewSite>,↵
cn=sites,cn=configuration,<ForestRootDN>
Using PowerShell
Move-ADDirectoryServer -Identity <DomainControllerName> -Site <NewSite>
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Discussion
When you install a new domain controller, a server object and nTDSDSA object for the
domain controller get added to the site topology. The Knowledge Consistency Checker
(KCC) and Intersite Topology Generator (ISTG) use these objects to determine whom
the domain controller should replicate with.
A domain controller is assigned to the site that has been mapped to the subnet it is
located on. If there is no subnet object that has an address range that contains the
domain controller’s IP address, the server object is added to the Default-First-SiteName site. If the domain controller should be in a different site, you’ll then need to
manually move it. It is a good practice to ensure that a subnet object that matches the
domain controller’s subnet is already in Active Directory before promoting the server
into the forest. That way you do not need to worry about moving it after the fact.
When moving a server object, remember that it has to be moved to a
Servers container within a site, not directly under the site itself.
Using a command-line interface
In the solution provided, you need to know the current site of the domain controller
you want to move. If you do not know the site it is currently in, you can use DSQuery
to find it. In fact, you can use DSQuery in combination with DSMove in a single com‐
mand line:
> for /F "usebackq" %i in ('dsquery server↵
-name"<DomainControllerName>"') do dsmove -newparent "cn=servers,↵
cn=Default-First-Site,cn=sites, cn=configuration,<ForestDN>" %i
This command is long, so we’ll break it up into three parts to clarify it. The first part
contains the for command extension that is built into the cmd.exe shell. When the /F
"usebackq" syntax is specified, it is typically used to iterate over output from a command
and perform certain functions on the output.
for /F "usebackq" %i in
The next part of the for loop contains the data to iterate over. In this case, we use
DSQuery to return the distinguished name of the server object for dc2:
('dsquery server -name "<DomainControllerName>"')
The last part executes a command for each result returned from DSQuery. In this case,
there should only be one result, so this command will run only once:
do dsmove -newparent "cn=servers,cn=Default-First-↵
Site,cn=sites,cn=configuration,<ForestDN>" %i
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See Also
Recipe 3.14 for finding a domain controller’s site; Recipe 4.20 for moving objects to
different containers
3.16. Finding the Services a Domain Controller
Is Advertising
Problem
You want to find the services that a domain controller is advertising.
Solution
The following command will display the list of services a domain controller is
advertising:
> dcdiag /v /s:<DomainControllerName> /test:advertising
Running this command on a typical domain controller will produce the following
output:
Starting test: Advertising
The DC dc1 is advertising itself as a DC and having a DS.
The DC dc1 is advertising as an LDAP server
The DC dc1 is advertising as having a writable directory
The DC dc1 is advertising as a Key Distribution Center
The DC dc1 is advertising as a time server
The DS dc1 is advertising as a GC.
You can also use nltest to get similar information:
> nltest /server:<DomainControllerName> /dsgetdc:<DomainName>
Running this command on a domain controller in the adatum.com domain will produce
the following output:
DC: \\dc1.adatum.com
Address: \\10.0.0.1
Dom Guid: ac0e4884-cf79-4c9d-8cd9-817e3bfdab54
Dom Name: adatum.com
Forest Name: adatum.com
Dc Site Name: Raleigh
Our Site Name: Raleigh
Flags: PDC GC DS LDAP KDC TIMESERV GTIMESERV WRITABLE DNS_DC DNS_DOMAIN
DNS_FOREST CLOSE_SITE
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In the previous example, GTIMESERV denotes a DC that is a master time
server. WRITABLE denotes a DC that holds a writable copy of the Active
Directory database. Prior to Windows Server 2008, only NT 4.0 BDCs
would not possess this flag. Since 2008, Read-Only Domain Controllers
will also lack the WRITABLE flag.
Discussion
The dcdiag /test:advertising command is a wrapper around the DsGetDcName
method. DsGetDcName returns a structure called DOMAIN_CONTROLLER_INFO that con‐
tains the list of services a domain controller provides. Table 3-4 contains the possible
values returned from this call.
Table 3-4. DOMAIN_CONTROLLER_INFO flags
Value Description
DS_DS_FLAG Directory server for the domain.
DS_GC_FLAG Global catalog server for the forest.
DS_KDC_FLAG Kerberos Key Distribution Center for the domain.
DS_PDC_FLAG Primary domain controller of the domain.
DS_TIMESERV_FLAG Time server for the domain.
DS_WRITABLE_FLAG Hosts a writable directory service.
See Also
MSDN: DsGetDcName; MSDN: DOMAIN_CONTROLLER_INFO
3.17. Restoring a Deleted Domain Controller in Windows
Server 2012
Problem
You want to restore the computer account of a domain controller that has been acci‐
dentally deleted.
Solution
Using a graphical user interface
The following solution requires that the Active Directory Recycle Bin feature has been
enabled and that the feature was enabled prior to the deletion of the domain controller
computer object.
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1. Launch the Active Directory Administrative Center.
2. In the left pane, select the domain and then double-click the Deleted Objects
container in the right pane.
3. In the Filter box near the top of the Active Directory Administrative Center, enter
the domain controller name to narrow down the displayed objects to the domain
controller object.
4. Right-click the domain controller object and then click Restore.
Using a command-line interface
This command-line solution uses a traditional restoration approach by performing an
authoritative restore. To restore the computer account, use the following sequence of
commands in Windows Server 2012:
> ntdsutil
> activate instance ntds
> authoritative restore> restore object <DomainControllerDN>
> quit
> exit
Restart the domain controller after running these commands.
Using PowerShell
The PowerShell solution requires that the Active Directory Recycle Bin feature be en‐
abled and that the feature was enabled prior to the deletion of the domain controller
computer object. To restore the computer account for a domain controller named DC1,
use the following PowerShell command:
Get-ADObject -Filter {Name -eq "dc1" -and ObjectClass -eq "computer"}↵
-IncludeDeletedObjects | Restore-ADObject
Discussion
The Active Directory Recycle Bin has greatly simplified the restoration of AD objects.
Now, deleted objects can be restored in their entirety without rebooting a domain con‐
troller or recovering data from backup media. In addition, the restore process is much
faster, literally just minutes.
Without the use of the Active Directory Recycle Bin, when you restore a deleted object
within Active Directory you have the option of performing an authoritative or a non‐
authoritative restore. In both cases, any changes that have been made to the AD database
subsequent to the time that the backup was taken will be replicated back to the restored
DC. With an authoritative restore, the version number of the object(s) being restored
is incremented so that the restored objects will “win” in the case of any replication
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collisions. In a case where you want to restore an object that has been inadvertently
deleted, you need to perform an authoritative restore to prevent the deletion from re‐
propagating to the restored domain controller. You can mark an entire restore as au‐
thoritative, or any subtree of your AD environment down to a single object (in this case,
the computer object for the DC that was deleted).
Using PowerShell
The PowerShell solution uses two filters: one for Name and one for ObjectClass. Al‐
though filtering by just the name will find and restore the object, it may also restore
noncomputer objects as well (e.g., an object in the msDFSR-Member object class will have
the same name). Instead of using two filters, you can also find the specific object that
you want to recover and then recover it directly by specifying the object GUID.
See Also
Chapter 16 for more on recovering and restoring Active Directory
3.18. Resetting the TCP/IP Stack on a Domain Controller
Problem
You want to uninstall and reinstall the TCP/IP stack on a domain controller as part of
a disaster recovery or troubleshooting operation.
Solution
Using a command-line interface
> netsh int tcp reset <Log_File_Name>
Discussion
Resetting the TCP/IP stack using netsh will remove all configuration information, in‐
cluding the default gateway and any configured DNS and WINS servers. This procedure
might be necessary during a disaster recovery situation where you’re restoring System
State data to a server with a dissimilar hardware configuration, for example, as the
restore process might corrupt the TCP/IP stack on the destination computer.
Using a command-line interface
In addition to resetting the TCP/IP stack, you can also reset Winsock using the following
command:
> netsh winsock reset
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Use this command with care, though, as resetting Winsock can cause network applica‐
tions such as antivirus scanners to malfunction and require reinstallation. A reboot is
required to complete the Winsock reset.
See Also
MS KB 299357 (How to reset Internet Protocol (TCP/IP))
3.19. Configuring a Domain Controller to Use an External
Time Source
Problem
You want to set the reliable time source for a domain controller.
Solution
Using the Registry
To configure a domain controller to sync to an external time provider, set the following
Registry keys:
[HKLM\System\CurrentControlSet\Services\W32Time\Parameters\]
Type: REG_SZ - "NTP"
[HKLM\System\CurrentControlSet\Services\W32Time\Config\]
AnnounceFlags: REG_DWORD - 10
[HKLM\System\CurrentControlSet\Services\W32Time\TimeProviders\]
NTPServer: REG_DWORD - 1
[HKLM SYSTEM\CurrentControlSet\Services\W32Time\Parameters\]
NTPServer: REG_SZ -<Peers>
[HKLM \SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\
NtpClient\]
SpecialPollInterval: REG_DWORD -<TimeBetweenPollsInSeconds>
[HKLM \SYSTEM\CurrentControlSet\Services\W32Time\Config\]
MaxPosPhaseCorrection: REG_DWORD -<MaximumForwardOffsetInSeconds>
[HKLM \SYSTEM\CurrentControlSet\Services\W32Time\Config\]
MaxNegPhaseCorrection: REG_DWORD -<MaximumBackwardOffsetInSeconds>
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<Peers> in the preceding code refers to a space-separated list of FQDNs
of external time servers. Each DNS name must be followed by ,0x1 for
the rest of these settings to take effect.
Once you have made these changes to the Registry, stop and restart the W32time service
by issuing the following commands:
> net stop w32time
> net start w32time
Using a command line
w32tm /config /syncfromflags:manual /manualpeerlist:<FQDNofTimeServer>
w32tm /config /update
Discussion
You should set a reliable time source on the PDC Emulator FSMO for only the forest
root domain. All other domain controllers sync their time either from that server, from
a PDC within their own domain, or from a designated time server on another domain
controller. The list of external time servers is stored in the Registry under the W32Time
Service Registry key: HKLM\SYSTEM\CurrentControlSet\Services\W32Time\Parame
ters\ntpserver.
If you want a domain controller such as the PDC to use an external time source, you
have to set the ntpserver Registry value along with the type value. The default value
for type on a domain controller is Nt5DS, which means that the domain controller will
use the Active Directory domain hierarchy to find a time source. You can override this
behavior and have a domain controller contact a non-DC time source by setting type
to NTP.
After setting the time server, the W32Time service should be restarted for the change
to take effect. You can check that the server was set properly by running the following
command:
> w32tm /query /computer:localhost /configuration
Since the PDC Emulator is the time source for the other domain controllers, you should
also make sure that it is advertising the time service, which you can do with the following
command:
> nltest /server:<DomainControllerName> /dsgetdc:<DomainDNSName> /TIMESERV
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To configure the PDC Emulator to use its own internal clock as a time
source instead of relying on an external clock, modify the HKLM\SYSTEM
\CurrentControlSet\Services\W32Time\Config\AnnounceFlags
DWORD value to contain a value of 0x0A.
The algorithm used by domain controllers to sync time gets quite complex. See the next
section for links to additional details on how the Windows time service works.
See Also
“Configure the Time Source for the Forest”; “How Windows Time Service Works”
3.20. Finding the Number of Logon Attempts Made
Against a Domain Controller
Problem
You want to find the number of logon requests a domain controller has processed.
Solution
The following query returns the number of logon requests processed:
> nltest /server:<DomainControllerName> /LOGON_QUERY
This will produce output similar to the following:
Number of attempted logons: 10542526
Discussion
The nltest /LOGON_QUERY command is a wrapper around the I_NetLogonControl2
method, and it can be useful to determine how many logon requests are being processed
by a server. Viewing the results of the command over a period of time and comparing
them against another DC in the same domain can also tell you if one domain controller
is being used significantly more or less than the others.
See Also
MSDN: I_NetLogonControl2
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3.21. Enabling the /3GB Switch to Increase the
LSASS Cache
Problem
You have installed more than 1 GB of memory on your 32-bit domain controllers and
want to enable the /3GB switch so that the LSASS process can use more memory.
Solution
Using a command-line interface
On a 32-bit Windows Server 2008 server, run the following command:
> bcdedit /set IncreaseUserVA 3072
Restart the computer.
Discussion
When computers are referred to as 32- or 64-bit computers, it means they support
memory addresses that are 32 or 64 bits long. This is the total available memory (virtual
and real) that can be processed by the system. Since the days of Windows NT, Microsoft
has split memory allocation in half by giving applications up to 2 GB and the Windows
kernel 2 GB of memory to use (32 bits of address space = 2^32 = 4 GB). In many cases,
administrators would rather allocate more memory to applications than to the kernel.
For this reason, Microsoft developed the /3GB switch to allow applications running on
32-bit versions of Windows to use up to 3 GB of memory, leaving the kernel with 1 GB.
This configuration is not necessary for 64-bit versions of Windows.
3.22. Enabling and Disabling the Global Catalog
Problem
You want to enable or disable the global catalog (GC) on a particular server.
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Solution
Using a graphical user interface
1. Open the Active Directory Sites and Services snap-in (dssite.msc).
2. Browse to the nTDSDSA object (NTDS Settings) underneath the server object for
the domain controller for which you want to enable or disable the global catalog.
3. Right-click on NTDS Settings and select Properties.
4. Under the General tab, check (to enable) or uncheck (to disable) the box beside
Global Catalog.
5. Click OK.
Using a command-line interface
In the following command, <ServerObjectDN> should be the server object DN, not
the DN of the nTDSDSA object:
> dsmod server "<ServerObjectDN>" -isgc yes|no
For example, the following command will enable the global catalog on DC1 in the Ra‐
leigh site:
> dsmod server
"cn=DC1,cn=servers,cn=Raleigh,cn=sites,cn=configuration,dc=adatum,dc=com"↵
-isgc Yes
You can also use AdMod with the following syntax and output to disable the GC; to
enable it, use options::{{.:CLR:1}}:
> adfind -b "cn=NTDS
Settings,cn=dc1,cn=Servers,cn=Raleigh,cn=Sites,cn=Configuration,dc=adatum,↵
dc=com" options -adcsv | admod options::{{.:SET:1}}
See Chapter 4 for information on safely modifying bitwise operators.
Using PowerShell
Set-ADObject "cn=NTDS Settings,cn="<DomainControllerName>,cn=Servers,↵
cn=<SiteName>,;cn=Sites,cn=Configuration,dc="<DomainName>,dc=<TopLevelDomain>"↵
-Replace @{Options='1'}
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Discussion
The first domain controller promoted into a forest is also made a global catalog (GC)
server by default. In a single-domain environment, the global catalog server incurs no
memory or bandwidth overhead beyond that of a domain controller, so you could con‐
figure each DC in a single-domain forest as a GC without any ill effects. In a multidomain
environment, however, each global catalog server will require additional disk space to
store a partial replica of other domains in the forest, and will require additional network
bandwidth to replicate with other GCs. For more details on DC and GC placement
planning, see Active Directory, Fifth Edition, by Brian Desmond et al. (O’Reilly).
The global catalog on a domain controller becomes enabled when the low-order bit on
the options attribute on the nTDSDSA object under the server object for the domain
controller is set to 1; it becomes disabled when it is set to 0. The DN of this object for
DC1 in the Default-First-Site-Name site looks like this:
cn=NTDSSettings,cn=DC1,cn=Default-First-Site-Name,cn=Sites,cn=Configuration,↵
dc=adatum,dc=com
After enabling the global catalog, it can take some time before the domain controller
can start serving as a global catalog server. The length of time is based on the amount
of data that needs to replicate and the type of connectivity between the domain con‐
troller’s replication partners. This is also dependent on the Global Catalog Partition
Occupancy setting, which is set in the HKLM\System\CurrentControlSet\Services
\NTDS\Parameters key on the GC itself, which specifies how many directory partitions
must be fully replicated to the GC before it is considered ready; this can range from no
occupancy requirement whatsoever, to requiring that all partitions be fully synchron‐
ized before the GC can begin servicing requests. After replication is complete, you
should see Event 1119 in the Directory Services log stating the server is advertising itself
as a global catalog. At that point you should also be able to perform LDAP queries against
port 3268 on that server. See Recipe 3.23 for more information on how to determine
whether global catalog promotion is complete.
See Also
Recipe 3.23 for determining whether global catalog promotion is complete; “Under‐
standing the Global Catalog”
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3.23. Determining Whether Global Catalog Promotion
Is Complete
Problem
You want to determine whether a domain controller is a global catalog server. After you
initially enable the global catalog on a domain controller, it can take some time for all
of the read-only naming contexts to replicate to it, depending on the number of domains,
the volume of directory data, and the underlying network topology.
Solution
Query the isGlobalCatalogReady attribute on the RootDSE for the domain controller.
A TRUE value means the server is a global catalog, and a FALSE value indicates it is not.
For more information on how to query the RootDSE, see Recipe 4.1.
You can also check the Directory Services Event Log in the Event Viewer MMC for the
presence of Event ID 1119, whose text reads as follows:
"This Windows Domain Controller is now a Global Catalog Server"
Using a command-line interface
To confirm that a domain controller in the adatum.com domain named dc1 is func‐
tioning as a global catalog server, use nltest with the following syntax:
> nltest /server:dc1.adatum.com /dsgetdc:adatum.com
If the DC in question is functioning as a GC, you’ll see output similar to the following:
> C:\>nltest /dsgetdc:adatum.com
> DC: \\dc1.adatum.com
> Address: \\10.0.0.1
> Dom Guid: ac0e4884-cf79-4c9d-8cd9-817e3bfdab54
> Dom Name: adatum.com
> Forest Name: adatum.com
> Dc Site Name: Raleigh
> Our Site Name: Raleigh
> Flags: PDC GC DS LDAP KDC TIMESERV GTIMESERV WRITABLE DNS_DC DNS_DOMAIN
> DNS_FOREST CLOSE_SITE
> The command completed successfully
Using PowerShell
Get-ADDomainController -Server <DomainControllerName> |↵
FT Name,IsGlobalCatalog -AutoSize
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Discussion
Once a server has completed initial replication of the global catalog, the attribute is
GlobalCatalogReady in the RootDSE will be set to TRUE. Another way to determine if
a domain controller has been at least flagged to become a global catalog is by checking
whether the options attribute on the nTDSDSA object for the server has been set to 1.
(Note that this does not necessarily mean the server is accepting requests as a global
catalog.) An additional query to the RootDSE as described in the “Solution” on page 89
or directly to port 3268 (the global catalog port) could also confirm that the appropriate
flag has been set.
See Also
Recipe 4.1 for viewing the RootDSE
3.24. Finding the Global Catalog Servers in a Forest
Problem
You want a list of the global catalog servers in a forest.
Solution
Using a command-line interface
To enumerate all GCs in a forest using DSQuery, use the following syntax:
> dsquery server -forest -isgc
Using PowerShell
To find all global catalogs in the current domain, use the following syntax:
Get-ADDomainController -Filter { IsGlobalCatalog -eq $true } | Select Name
To find all global catalogs in the forest, use the following two PowerShell commands:
$GCs = Get-ADForest
$GCs.GlobalCatalogs
Discussion
To find the global catalog servers in a forest, you need to query for NTDS Settings
objects that have the low-order bit of the options attribute equal to 1 under the Sites
container in the Configuration naming context. That attribute determines whether a
domain controller should be a global catalog server, but it does not necessarily mean it
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is a global catalog server yet. See Recipe 3.23 for more information on how to tell whether
a server marked as a global catalog is ready to accept requests as one.
See Also
Recipe 3.23 for determining whether global catalog promotion is complete
3.25. Finding the Domain Controllers or Global Catalog
Servers in a Site
Problem
You want a list of the domain controllers or global catalog servers in a specific site.
Solution
Using a graphical user interface
1. Open the Active Directory Administrative Center.
2. In the left pane, double-click the domain name.
3. Double-click the Domain Controllers OU.
4. In the right pane, you can view the Domain Controller Type column to see if a
domain controller is a global catalog server.
Global catalog servers will have the appropriate box checked beside Global Catalog.
Using PowerShell
To find all of the domain controllers in SiteA for the current domain, use the following
syntax:
Get-ADDomainController -Filter { Site -eq "SiteA" } | FL Name
To find all GCs in SiteA for the current domain, use the following syntax:
Get-ADDomainController -Filter { Site -eq "SiteA" -and↵
( IsGlobalCatalog -eq "True" )} | FL Name
To find all global catalogs in SiteA in the entire forest, use the following syntax:
$for = [System.DirectoryServices.ActiveDirectory.Forest]::getCurrentForest()
$dom.FindAllGlobalCatalogs("SiteA")
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Discussion
Each domain controller has a server object within the Servers container for the site it
is a member of (e.g., cn=DC1,cn=Servers,cn=MySite,cn=site,cn=configura
tion,dc=adatum,dc=com). Since other types of servers can have server objects in a site’s
Servers container, domain controllers are differentiated by the nTDSDSA object that is
a child of the server object (e.g., cn=NTDSSettings,cn=DC1,cn=Servers,cn=My
Site,cn=site,cn=configuration,dc=adatum,dc=com). Querying for this nTDSDSA
object will return a list of domain controllers in the site. Locating global catalog servers
consists of the same query, except where the low-order bit of the options attribute of
the nTDSDSA object is equal to 1. Note that this may not be available if replication has
not completed after enabling the GC.
3.26. Finding Domain Controllers and Global Catalogs
via DNS
Problem
You want to find domain controllers or global catalogs using DNS lookups.
Solution
Domain controllers and global catalog servers are represented in DNS as SRV records.
You can query SRV records using nslookup by setting type=SRV, such as in the following:
> nslookup
Default Server: dns01.adatum.com
Address: 10.1.2.3
> set type=SRV
You then need to issue the following query to retrieve all writable domain controllers
for the specified domain:
> _ldap._tcp.<DomainDNSName>
You can issue a similar query to retrieve global catalogs:
> _gc._tcp
You can even find the domain controllers or global catalogs that are in a particular site
or that cover a particular site by querying the following:
> _ldap._tcp.<SiteName>._sites
> _gc._tcp.<SiteName>._sites
See Recipe 11.20 for more information on site coverage.
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Discussion
One of the benefits of Active Directory over its predecessor, Windows NT, is that it relies
on DNS for name resolution, which is the standard for name resolution on the Internet
and on most TCP/IP-based networks. Active Directory uses DNS to locate servers that
serve a particular function, such as a domain controller for a domain, global catalog
server, PDC Emulator, or KDC. It also uses the site topology information stored in
Active Directory to populate site-specific records for domain controllers.
The DC locator process relies on this information in DNS to direct clients to the most
optimal server when logging in. Reliance on DNS makes it easy to troubleshoot prob‐
lems related to clients finding domain controllers. If you know the site a client is in, you
can make a few DNS queries to determine which domain controller they should be using
to authenticate.
The resource records that a domain controller registers in DNS can be restricted, if you
have a lag site configured, for example, so querying DNS may return only a subset of
the actual domain controllers that are available. See Recipes 12.13 and 12.14 for more
information.
See Also
Recipe 12.13; Recipe 12.14; Recipe 3.32 for finding the PDC Emulator via DNS; MS KB
267855 (Problems with Many Domain Controllers with Active Directory Integrated
DNS Zones); RFC 2782, “A DNS RR for Specifying the Location of Services (DNS SRV)”
3.27. Changing the Preference for a Domain Controller
Problem
You want a particular domain controller to be used less frequently for client requests,
or not at all. This may be necessary if a particular domain controller is overloaded,
perhaps due to numerous application requests.
Solution
You can modify the Priority or Weight field in SRV resource records by modifying the
registry on the domain controller. Open regedit or regedit32 on the domain controller
and browse to the following key: HKLM\SYSTEM\CurrentControlSet\Services\Netlo
gon\Parameters. To configure the priority, add a REG_DWORD with the name LdapSrv
Priority. To configure the weight, add a REG_DWORD with the name LdapSrvWeight.
After you make the change, the %SystemRoot%\System32\Config\netlogon.dns file
should be updated and the DDNS updates sent to the DNS server within an hour. You
can also restart the NetLogon service to expedite the process.
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Discussion
Each domain controller registers several SRV records that clients use as part of the DC
locator process to find the closest domain controller. Two fields of the SRV record let
clients determine which server to use when multiple possibilities are returned. The
Priority field is used to dictate whether a specific server or set of servers should always
be contacted over others unless otherwise unavailable. A server with a higher priority
(i.e., lower Priority field value) will always be contacted before a server with a lower
priority. For example, if DC1 has an SRV priority of 5 and DC2 has an SRV priority of
10, DC1 will always be used unless it is unavailable.
The Weight field, on the other hand, determines the percentage of time clients should
use a particular server. You can easily calculate the percentage by dividing the weight
by the sum of all weights for servers with the same priority. If servers DC1, DC2, and
DC3 have weights of 1, 2, and 3, respectively, then DC1 will be contacted one out of six
times or (1 / (3 + 2 + 1)), DC2 will be contacted two out of every six times or 1/3 (2 / (3
+ 2 + 1)), and DC3 will be contacted three out of every six times or 1/2 (3 / (3 + 2 + 1)).
Here is an example of how the SRV records look with these weights:
C:\> nslookup -type=SRV _ldap._tcp.dc._msdcs.adatum.com
Server: dns01.adatum.com
Address: 172.16.168.183
_ldap._tcp.dc._msdcs.adatum.com SRV service location:
priority = 0
weight = 1
port = 389
svr hostname = dc1.adatum.com
_ldap._tcp.dc._msdcs.adatum.com SRV service location:
priority = 0
weight = 2
port = 389
svr hostname = dc2.adatum.com
_ldap._tcp.dc._msdcs.datum.com SRV service location:
priority = 0
weight = 3
port = 389
svr hostname = dc3.datum.com
In certain situations, having this capability can come in handy. For example, the server
acting as the PDC FSMO role owner typically receives more traffic from clients simply
because of the nature of tasks that the PDC FSMO has to handle. If you find a certain
server, like the PDC FSMO, has considerably higher load than the rest of the servers,
you could change the priority or weight of the SRV records so that the server is used
less often during the DC locator process. You can increase the Priority to eliminate its
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use unless all other domain controllers fail, or modify the Weight to reduce how often
it will be used.
You can modify this information manually within the DNS Management Console, or
for multiple DCs using Group Policy Objects in the Computer Configuration\Admin
istrative Templates\System\Net Logon\DC Locator DNS Records GPO node.
See Also
MS KB 232025 (Description of the DNS SRV Resource Record Type)
3.28. Disabling the Global Catalog Requirement for
User Logon
Problem
You want to disable the requirement for a global catalog server to be reachable when a
user logs in to a Windows domain.
Solution
See Recipe 7.12 for information on enabling universal group caching, which can reduce
the need to contact a global catalog server during logon for universal group expansion.
3.29. Finding the FSMO Role Holders
Problem
You want to find the domain controllers that are acting as one of the FSMO roles.
Solution
Using a graphical user interface
For the Schema Master:
1. Open the Active Directory Schema snap-in.
2. Right-click on Active Directory Schema in the left pane and select Operations
Master.
For the Domain Naming Master:
1. Open the Active Directory Domains and Trusts snap-in (domain.msc).
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2. Right-click on Active Directory Domains and Trusts in the left pane and select
Operations Master.
For the PDC Emulator, RID Master, and Infrastructure Master:
1. Open the Active Directory Users and Computers snap-in (dsa.msc).
2. Make sure you’ve targeted the correct domain.
3. Right-click on Active Directory Users and Computers in the left pane and select
Operations Masters.
4. Work your way through the individual tabs for the PDC, RID, and Infrastructure
roles.
Using a command-line interface
In the following command, you can leave out the /Domain <DomainDNSName> option to
query the domain you are currently logged in to:
> netdom query fsmo /Domain:<DomainDNSName>
To query the owner of an individual FSMO role, you can use the dsquery server
command shown here, where <Role> can be schema, name, infr, pdc, or rid:
> dsquery server -hasfsmo <Role>
Using PowerShell
The following command will query the forest-level FSMO roles:
Get-ADForest | FL DomainNamingMaster,SchemaMaster
The following command will query the domain-level FSMO roles for the specified
domain:
Get-ADDomain -Identity <DomainDNSName> |↵
FL InfrastructureMaster,PDCEmulator,RIDMaster
Discussion
Several Active Directory operations are sensitive, such as updating the schema, and
therefore need to be restricted to a single domain controller to prevent corruption of
the AD database. This is because Active Directory cannot guarantee the proper
evaluation of these functions in a situation where they may be invoked from more than
one DC. The FSMO mechanism is used to limit these functions to a single DC.
Five designated FSMO roles correspond to these sensitive functions. A FSMO role can
apply either to an entire forest or to a specific domain. Each role is stored in the fSMOR
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oleOwner attribute on various objects in Active Directory depending on the role.
Table 3-5 contains a list of FSMO roles.
Table 3-5. FSMO roles
Role Description fSMORoleOwner location Domain- or
forest-wide?
Schema Processes schema updates. cn=Schema,cn=Configura
tion,<ForestDN>
Forest
Domain Naming Processes the addition, removal, and renaming of
domains.
cn=Partitions cn=Configu
ration,<ForestDN>
Forest
Infrastructure Maintains references to objects in other domains. cn=Infrastructure,<Do
mainDN>
Domain
RID Handles RID pool allocation for the domain
controllers in a domain.
cn=RidManager$,cn=Sys
tem,<DomainDN>
Domain
PDC Emulator Receives preferential password replication,
handles user authentication after another DC
reports bad password, handles account lockouts.
<DomainDN> Domain
Using PowerShell
For a quick method of retrieving the FSMO role holders in a forest or domain, simply
retrieve the properties of the forest or domain object, as follows:
Get-ADForest
or:
Get-ADDomain
See Also
Recipe 3.13; “Using Ntdsutil.exe to transfer or seize FSMO roles to a domain controller”
3.30. Transferring a FSMO Role
Problem
You want to transfer a FSMO role to a different domain controller. This may be necessary
if you need to take a current FSMO role holder down for maintenance.
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Solution
Using a graphical user interface
1. Use the same directions as described in Recipe 3.29 for viewing a specific FSMO,
except target (i.e., right-click and select Connect to Domain Controller) the domain
controller you want to transfer the FSMO to before selecting Operations Master.
2. Click the Change button.
3. Click OK twice.
You should then see a message stating whether the transfer was successful.
Using a command-line interface
The following will transfer the PDC Emulator role to <NewRoleOwner> (see “Discus‐
sion” on page 96 section for information on transferring the other roles):
> ntdsutil roles conn "co t s <NewRoleOwner>" q "transfer PDC" q q
Using PowerShell
The following command will transfer the PDC Emulator role to a DC named DC1:
Move-ADDirectoryServerOperationMasterRole DC1 -PDCEmulator
The following will transfer the RID Master role to another DC named DC1; this syntax
can be used for all FSMO role holders except for the PDC Emulator:
Move-ADDirectoryServerOperationMasterRole DC1 -RIDMaster
Discussion
The first domain controller in a new forest is assigned the two forest-wide FSMO roles
(schema and domain naming). The first domain controller in a new domain gets the
other three domain-wide roles. It is very likely you’ll need to move the roles around to
different domain controllers at some point. Also, when you need to decommission a
domain controller that is currently a FSMO role owner (either permanently or for a
significant period of time), you’ll want to transfer the role beforehand.
If you plan to install a hotfix or do some other type of maintenance that only necessitates
a quick reboot, you may not want to go to the trouble of transferring the FSMO role.
This is because some FSMO roles are more time-critical than others, and some come
into use on a far more frequent basis. For example, the PDC Emulator role is used
extensively (and therefore should be transferred to a domain controller of equal or better
capacity as a best practice), but the Schema Master is needed only when you are ex‐
tending the schema by installing a new software package, such as Microsoft Exchange.
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If a FSMO role owner becomes unavailable before you can transfer it, you’ll need to
seize the role (see Recipe 3.31).
Using a command-line interface
Any role can be transferred using ntdsutil by replacing "transfer PDC" in the solution
with one of the following:
• "transfer domain naming master"
• "transfer infrastructure master"
• "transfer RID master"
• "transfer schema master"
Using PowerShell
The FSMO roles can be shortened to simplify the commands to move the roles. Because
each role starts with a unique letter, you can transfer them by just referring to them by
the first letter of the role name. In addition, you can transfer multiple roles in one
command. The following command will transfer all five roles to DC1:
Move-ADDirectoryServerOperationMasterRole DC1 -S,D,I,P,R
See Also
Recipe 3.29 for finding FSMO role holders; Recipe 3.31 for seizing a FSMO role; “Using
Ntdsutil.exe to transfer or seize FSMO roles to a domain controller”
3.31. Seizing a FSMO Role
Problem
You need to seize a FSMO role because the current role holder is down and will not be
restored.
Solution
Using a command-line interface
The following will seize the PDC Emulator role to <NewRoleOwner>:
> ntdsutil roles conn "co t s <NewRoleOwner>" q "seize PDC" q q
Any of the other roles can be transferred as well using ntdsutil by replacing "seize
PDC" in the previous solution with one of the following:
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• "seize domain naming master"
• "seize infrastructure master"
• "seize RID master"
• "seize schema master"
Using PowerShell
The following will seize the PDC Emulator role to <NewRoleOwner>:
> Move-ADDirectoryServerOperationMasterRole <NewRoleOwner> -PDCEmulator -Force
Discussion
Seizing a FSMO role should not be taken lightly. The general recommendation is to
seize a FSMO role only when you cannot possibly bring the previous role holder back
online. One reason that seizing a role is problematic is that you could possibly lose data.
For example, let’s say that you extended the schema and immediately after it was ex‐
tended the Schema FSMO went down. If you could not bring that server back online,
those extensions may not have replicated before the server went down. You would need
to determine whether any of the schema extensions replicated and, if not, reextend the
schema. Other issues can result from losing the RID FSMO, where duplicate RID pools
may be allocated. See Recipe 3.29 for more information.
See Also
Recipe 3.29 for finding FSMO role holders; Recipe 3.30 for transferring a FSMO role;
“Using Ntdsutil.exe to transfer or seize FSMO roles to a domain controller”
3.32. Finding the PDC Emulator FSMO Role Owner via DNS
Problem
You want to find the PDC Emulator for a domain using DNS.
Solution
Using a command-line interface
> nslookup -type=SRV _ldap._tcp.pdc._msdcs.<DomainDNSName>
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Discussion
The PDC Emulator FSMO role is the only FSMO role that is stored in DNS. Like many
of the other Active Directory−related DNS records, the PDC record is stored as an SRV
record under _ldap._tcp.pdc._msdcs.<DomainDNSName> where <DomainDNSName> is
the domain the PDC is in. This allows your Active Directory clients to use normal DNS
name resolution to locate the PDC Emulator for their domain.
See Also
Recipe 3.26 for finding domain controllers via DNS
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CHAPTER 4
Searching and Manipulating Objects
4.0. Introduction
Active Directory is based on Lightweight Directory Access Protocol (LDAP) and sup‐
ports the LDAP version 3 specification defined in RFC 2251. And while many of the
AD tools and interfaces, such as ADSI, abstract and streamline LDAP operations to
make things easier, any good AD administrator or developer must have a thorough
understanding of LDAP to fully utilize Active Directory. This chapter will cover some
of the LDAP-related tasks you may need to perform when working with Active Direc‐
tory, along with other tasks related to searching and manipulating objects within the
directory.
The Anatomy of an Object
The Active Directory schema is composed of a hierarchy of classes that define the types
of objects that can be created within Active Directory, as well as the different attributes
they can possess. These classes support inheritance, which enables developers to reuse
existing class definitions for more than one type of object; for example, the descrip
tion attribute is available with every type of AD object, but the attribute itself is defined
only once within the schema. At the top of the inheritance tree is the top class, from
which every class in the schema is derived. Table 4-1 contains a list of some of the
attributes that are available from the top class, and subsequently are defined on every
object that is created in Active Directory.
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Table 4-1. Common attributes of objects
Attribute Description
cn RDN attribute for most object classes, also referred to as the common name.
whenCreated Timestamp when the object was created. See Recipe 4.26 for more information.
description Multivalued attribute that can be used as a generic field for storing a description of the object.
Although this attribute is multivalued, objects such as users and groups can have only one value
populated due to legacy support requirements.
displayName Name of the object displayed in administrative interfaces.
distinguishedName Distinguished name of the object.
whenChanged Timestamp when the object was last changed by the local server. See Recipe 4.26 for more
information.
name RDN of the object. The value of this attribute will mirror the naming attribute (e.g., cn, ou, dc).
nTSecurityDescriptor Security descriptor assigned to the object.
objectCategory Used as a grouping mechanism for objects with a similar purpose (e.g., Person).
objectClass List of classes from which the object’s class was derived.
objectGUID Globally unique identifier for the object.
uSNChanged Update sequence number (USN) assigned by the local server after the last change to the object
(can include creation).
uSNCreated USN assigned by the local server when the object was created.
4.1. Viewing the RootDSE
Problem
You want to view attributes of the RootDSE, which can be useful for discovering basic
information about a forest, domain, or domain controller without hardcoding the name
of a particular naming context into a query.
Solution
Using a graphical user interface
1. Open LDP.
2. From the menu, select Connection→Connect.
3. For Server, enter a domain controller or domain name, or leave it blank to do a
serverless bind.
4. For Port, enter 389.
5. Click OK.
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6. The contents of the RootDSE will be shown in the right pane.
Using a command-line interface
To display the RootDSE of a domain controller using AdFind, use the following syntax:
> adfind -rootdse
Using PowerShell
Get-ADRootDSE
You’ll see results similar to the following (truncated for readability):
configurationNamingContext: cn=Configuration,dc= adatum,dc=com
currentTime: 10/9/2012 9:27:38 AM
defaultNamingContext: dc=adatum,dc=com
dnsHostName: dc1.adatum.com
domainControllerFunctionality: Windows2012
domainFunctionality: Windows2012Domain
dsServiceName: cn=NTDS Settings,cn=DC1,cn=Servers,cn=Default-First-Site-Name,↵
cn=Sites,cn=Configuration,dc=adatum,dc=com
forestFunctionality: Windows2012Forest
highestCommittedUSN: 28013
isGlobalCatalogReady: {TRUE}
isSynchronized: {TRUE}
ldapServiceName: adatum.com:dc1$@ADATUM.COM
namingContexts: {dc=adatum,dc=com, cn=Configuration,dc=adatum,dc=com,
cn=Schema,cn=Configuration,dc=adatum,dc=com,dc=DomainDnsZones,dc=adatum,↵
dc=com...}
rootDomainNamingContext: dc=adatum,dc=com
schemaNamingContext: cn=Schema,cn=Configuration,dc=adatum,dc=com
serverName: cn=dc1,cn=Servers,cn=Default-First-Site-Name,cn=Sites,↵
cn=Configuration,dc=adatum,dc=com
subschemaSubentry: cn=Aggregate,cn=Schema,cn=Configuration,dc=adatum,dc=com
supportedCapabilities: {1.2.840.113556.1.4.800 (LDAP_CAP_ACTIVE_DIRECTORY_OID),↵
;1.2.840.113556.1.4.1670(LDAP_CAP_ACTIVE_DIRECTORY_V51_OID),↵
;1.2.840.113556.1.4.1791(LDAP_CAP_ACTIVE_DIRECTORY_LDAP_INTEG_OID),↵
;1.2.840.113556.1.4.1935(LDAP_CAP_ACTIVE_DIRECTORY_V61_OID)...}
supportedControl: {1.2.840.113556.1.4.319(LDAP_PAGED_RESULT_OID_STRING),↵
;1.2.840.113556.1.4.801(LDAP_SERVER_SD_FLAGS_OID),↵
;1.2.840.113556.1.4.473(LDAP_SERVER_SORT_OID),↵
;1.2.840.113556.1.4.528(LDAP_SERVER_NOTIFICATION_OID)...}
supportedLDAPPolicies: {MaxPoolThreads, MaxDatagramRecv, MaxReceiveBuffer,↵
; InitRecvTimeout...}
supportedLDAPVersion: {3, 2}
supportedSASLMechanisms: {GSSAPI, GSS-SPNEGO, EXTERNAL, DIGEST-MD5}
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Discussion
The RootDSE was originally defined in RFC 2251 as part of the LDAPv3 specification.
It is not part of the Active Directory namespace per se. It is a synthetic object that is
maintained separately by each domain controller.
The RootDSE can be accessed anonymously using LDP; the command-line and Pow‐
erShell solutions use the credentials of the currently logged-on user unless you specify
an alternate username and password. In the CLI and PowerShell solutions, serverless
binds were used against the RootDSE. In that case, the DC Locator process is used to
find a domain controller in the domain you authenticate against. This can also be ac‐
complished with LDP by not entering a server name from the Connect dialog box.
The RootDSE is key to writing portable AD-enabled applications. It provides a mech‐
anism to programmatically determine the distinguished names of the various naming
contexts (among other things), which means that you do not need to hardcode that
information in scripts and programs.
See Also
RFC 2251; MS KB 219005 (Windows 2000: LDAPv3 RootDSE); MSDN: IADsProper‐
tyEntry; MSDN: IADsProperty Value; MSDN: IADs::Get MSDN: IADs::GetEx
4.2. Viewing the Attributes of an Object
Problem
You want to view one or more attributes of an object.
Solution
Using a graphical user interface
1. Open LDP.
2. From the menu, select Connection→Connect.
3. For Server, enter the name or IP address of a domain controller or domain that
contains the object.
4. For Port, enter 389.
5. Click OK.
6. From the menu, select Connection→Bind.
7. Accept the default and bind as the currently logged on user or select the option to
bind with credentials and then enter the credentials.
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8. Click OK.
9. From the menu, select View→Tree.
10. For BaseDN, type the DN of the object you want to view.
11. For Scope, select Base.
12. Click OK.
Using a command-line interface
To obtain a list of attributes for a particular object using DSQuery, use the following
syntax:
> dsquery * "<ObjectDN>" -scope base -attr *
To query for an object using AdFind, use the following syntax:
> adfind -b <Parent Container DN> -f cn=<Object CN> -tdcgt
Using PowerShell
To get the attributes of the built-in Administrator account, run the following PowerShell
command:
Get-ADUser -Identity Administrator -Properties *
An example of the output is shown here:
AccountExpirationDate :
accountExpires : 0
AccountLockoutTime :
AccountNotDelegated : False
adminCount : 1
AllowReversiblePasswordEncryption : False
BadLogonCount : 0
badPasswordTime : 129934507947486667
badPwdCount : 0
CannotChangePassword : False
CanonicalName : adatum.com/Users/Administrator
Certificates : {}
City :
CN : Administrator
codePage : 0
Company :
CompoundIdentitySupported : {}
Country :
countryCode : 0
Created : 9/27/2012 11:16:45 AM
createTimeStamp : 9/27/2012 11:16:45 AM
Deleted :
Department :
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Description : Built-in account for administering the
computer/domain
DisplayName :
DistinguishedName : cn=Administrator,cn=Users,dc=adatum,dc=com
Division :
DoesNotRequirePreAuth : False
dSCorePropagationData : {9/27/2012 11:34:42 AM,↵
9/27/2012 11:34:42 AM,↵
9/27/2012 11:19:31 AM,↵
1/1/1601 10:12:16 AM}
EmailAddress :
EmployeeID :
EmployeeNumber :
Enabled : True
Fax :
GivenName :
HomeDirectory :
HomedirRequired : False
HomeDrive :
HomePage :
HomePhone :
Initials :
instanceType : 4
isCriticalSystemObject : True
isDeleted :
KerberosEncryptionType : {}
LastBadPasswordAttempt : 9/29/2012 8:53:14 PM
LastKnownParent :
lastLogoff : 0
lastLogon : 129942736428265971
LastLogonDate : 10/9/2012 9:27:17 AM
lastLogonTimestamp : 129942736379503412
LockedOut : False
logonCount : 29
logonHours : {255, 255, 255, 255...}
LogonWorkstations :
Manager :
MemberOf : {cn=Group Policy Creator
Owners,cn=Users,dc=adatum,dc=com, cn=Domain
Admins,cn=Users,dc=adatum,dc=com, cn=Enterprise
Admins,cn=Users,dc=adatum,dc=com, cn=Schema
Admins,cn=Users,dc=adatum,dc=com...}
MNSLogonAccount : False
MobilePhone :
Modified : 10/9/2012 9:27:17 AM
modifyTimeStamp : 10/9/2012 9:27:17 AM
msDS-AuthenticatedAtDC : {cn=2012-DC05,OU=Domain
Controllers,dc=adatum,dc=com}
msDS-User-Account-Control-Computed : 0
Name : Administrator
nTSecurityDescriptor : System.DirectoryServices.↵
ActiveDirectorySecurity
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ObjectCategory : cn=Person,cn=Schema,cn=Configuration,↵
dc=adatum,dc=com
ObjectClass : user
ObjectGUID : c897bc0a-b5d4-4025-8c10-b696e45ce780
objectSid : S-1-5-21-3384837461-4027165227-↵
453512602-500
Office :
OfficePhone :
Organization :
OtherName :
PasswordExpired : False
PasswordLastSet : 9/27/2012 10:18:17 AM
PasswordNeverExpires : False
PasswordNotRequired : False
POBox :
PostalCode :
PrimaryGroup : cn=Domain Users,cn=Users,dc=adatum,dc=com
primaryGroupID : 513
PrincipalsAllowedToDelegateToAccount : {}
ProfilePath :
ProtectedFromAccidentalDeletion : False
pwdLastSet : 129932398979898472
SamAccountName : Administrator
sAMAccountType : 805306368
ScriptPath :
sDRightsEffective : 15
ServicePrincipalNames : {}
SID : S-1-5-21-3384837461-4027165227-↵
453512602-500
SIDHistory : {}
SmartcardLogonRequired : False
State :
StreetAddress :
Surname :
Title :
TrustedForDelegation : False
TrustedToAuthForDelegation : False
UseDESKeyOnly : False
userAccountControl : 512
userCertificate : {}
UserPrincipalName :
uSNChanged : 28008
uSNCreated : 8196
whenChanged : 10/9/2012 9:27:17 AM
whenCreated : 9/27/2012 11:16:45 AM
Discussion
Objects in Active Directory are made up of a collection of attributes. Attributes can be
single- or multivalued. Each attribute also has an associated syntax that is defined in the
schema. See Recipe 10.6 for a complete list of syntaxes.
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Using a graphical user interface
You can customize the list of attributes returned from a search with LDP by modifying
the Attributes: field under Options→Search. To include all attributes, enter an asterisk
(*). To modify the default subset of attributes that are returned, enter a
semicolon-separated list of attributes. You can also use the numeric attribute ID instead
of the attribute name, such as using 1.1 in place of distinguishedName.
Using a command-line interface
The -attr option for the dsquery command accepts a whitespace-separated list of at‐
tributes to display. Using an asterisk (*) will return all default attributes.
When using AdFind, you have several shortcut switches to reduce the amount of typing
you need to do. If you are searching for an object in the default container, you can use
the –default switch rather than something like –b dc=contoso,dc=com. Likewise, if
you are querying the Configuration NC, you can use the –config switch, -root for the
root partition, or –schema for the Schema partition. If you want to query a subcontainer
of one of these partitions, you can add the –rb switch, which stands for Relative Base.
See Also
Recipe 10.6; MSDN: IADsPropertyEntry; MSDN: IADsPropertyList; MSDN: ADSTY‐
PEENUM; MSDN: IADs::GetInfo; Active Directory, Fifth Edition, by Brian Desmond
et al. (O’Reilly)
4.3. Counting Objects in Active Directory
Problem
You want to retrieve the number of directory objects that meet the result of an LDAP
query.
Solution
Using a graphical user interface
1. Open LDP.
2. From the menu, select Connection→Connect.
3. For Server, enter the name or IP address of a domain controller or the domain that
contains the object.
4. For Port, enter 389.
5. Click OK.
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6. From the menu, select Connection→Bind.
7. Accept the default and bind as the currently logged on user or select the option to
bind with credentials and then enter the credentials.
8. Click OK.
9. From the menu, select Browse→Search.
10. Enter the base DN, scope, and LDAP filter of the objects that you’re looking for.
11. Click Options and remove the checkmark next to Display Results. This will display
the number of objects returned by the query without displaying the details of the
items that are returned.
12. Click OK and then click Run to perform the query.
Using a command-line interface
To retrieve a count of objects that match a particular query, use the following syntax:
> adfind -b <Search Base> -s <Scope> -f <Search Filter> -c
For example, retrieving the number of user objects in the adatum.com domain would
use the following syntax:
> adfind -default -f "(&(objectclass=user)(objectcategory=person))" -c
>
> AdFind V01.46.00cpp Joe Richards (joe@joeware.net) March 2012
>
> Using server: dc1.adatum.com:389
> Directory: Windows Server 8
> Base DN: dc=adatum,dc=com
>
> 5 Objects returned
Using PowerShell
The following example will query Active Directory for a list of user objects in the current
domain and return the count:
Get-ADObject -Filter {(objectClass -eq "user") -and ↵
(objectCategory -eq "person")} | Measure-Object | FL Count
To retrieve a count of all of the computer objects in the current domain, run the following
command:
Get-ADObject -Filter {(objectClass -eq "user") -and ↵
(objectCategory -eq "computer")} | Measure-Object | FL Count
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Discussion
Using PowerShell
The PowerShell commands can target a specific container or OU, as follows:
Get-ADObject -SearchBase "OU=Branches,dc=adatum,dc=com"↵
-Filter {(objectClass -eq "user") -and (objectCategory -eq "person")} |↵
Measure-Object | FL Count
Be careful with the filtering. The class and category of the object must be combined to
accurately target user objects.
There are other ways to filter, too. In this recipe, we’ve used an efficient filtering method
while keeping the commands easy to use. However, in large environments, using LDAP
filtering can be a bit faster than standard filtering. The following command counts all
of the user objects in the current domain and uses LDAP filtering:
Get-ADObject -LDAPFilter "(&(objectCategory=Person)(objectClass=User)) " |↵
Measure-Object | FL Count
4.4. Using LDAP Controls
Problem
You want to use an LDAP control as part of an LDAP operation.
Solution
Using a graphical user interface
1. Open LDP.
2. From the menu, select Options→Controls.
3. Under Load Predefined, select the control you want to use. The control should
automatically be added to the list of Active Controls.
4. Under Value, enter the value for the control.
5. Under Control Type, select whether the control is server-side or client-side.
6. Check the box beside Critical if the control is critical.
7. Click OK.
8. At this point, you will need to invoke the LDAP operation (such as Search) that will
use the control. In the dialog box for any operation, click Options and ensure that
the Extended option is checked before initiating the operation.
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Using a command-line interface
The AdFind and AdMod utilities will enable a number of LDAP controls, either by
default or through the use of various command-line switches. For example, the –show
del switch will invoke the Show Deleted Objects LDAP control, and -stats will invoke
the Show Stats control.
Using PowerShell
PowerShell leverages LDAP controls in some built-in parameters of various cmdlets.
For example, the Get-ADObject cmdlet has a parameter to include deleted objects in
searches. The –IncludeDeletedObjects parameter uses LDAP controls as part of the
command.
Discussion
LDAP controls were defined in the LDAPv3 specification as a way to extend LDAP and
its operations without breaking the protocol. Many controls have been implemented,
some of which are used when searching the directory (e.g., paged searching, Virtual List
View [VLV], finding deleted objects, and attribute scoped query), and some are needed
to do certain modifications to the directory (e.g., cross-domain object moves, tree delete,
and permissive modify). Controls can be marked as critical, which means they must be
processed with the request or an error is returned. If an unsupported control is not
flagged as critical, the server can continue to process the request and ignore the control.
The complete list of controls supported by Active Directory is included in Table 4-2.
Table 4-2. LDAP controls supported by Active Directory
Name OID Description
Permit No-Opt Modify 1.2.840.113556.1.4.1413 Allows duplicate adds of the same value for an attribute or deletion of an
attribute that has no values to succeed (normally, it would fail in that
situation).
Return Deleted Objects 1.2.840.113556.1.4.417 Used to inform the server to return any deleted objects that matched the
search criteria.
Cross Domain Move 1.2.840.113556.1.4.521 Used to move objects between domains.
Set change
notifications
1.2.840.113556.1.4.528 Used by clients to register for notification of when changes occur in the
directory.
Delayed Write 1.2.840.113556.1.4.619 Used to inform the server to return after directory modifications have been
written to memory, but before they have been written to disk. This can speed
up processing of a lot of modifications.
Security Descriptor
Flags
1.2.840.113556.1.4.801 Used to pass flags to the server to control certain security descriptor options.
Subtree Delete 1.2.840.113556.1.4.805 Used to delete portions of the directory tree, including any child objects.
Verify Name Existence 1.2.840.113556.1.4.1338 Used to target a specific GC server that is used to verify DN-valued attributes
that are processed during addition or modification operations.
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Name OID Description
No referrals generated 1.2.840.113556.1.4.1339 Informs the server not to generate any referrals in a search response.
Domain or phantom
scope
1.2.840.113556.1.4.1340 Used to pass flags to the server to control search options.
Search Stats 1.2.840.113556.1.4.970 Used to return statistics about an LDAP query. See Recipe 15.8 for an example.
Attribute Scoped Query 1.2.840.113556.1.4.1504 Used to force a query to be based on a specific DN-valued attribute. This
control is new to Windows Server 2003. See Recipe 4.8 for an example.
Extended DN 1.2.840.113556.1.4.529 Used to return an object’s GUID and SID (for security principals) as part of its
distinguished name.
Quota SID 1.2.840.113566.1.4.1852 Used to pass the SID of a security principal in order to query constructed
attributes such as ms-DS-Quota-Effective and ms-DS-QuotaUsed.
Paged Results 1.2.840.113556.1.4.319 Instructs the server to return search results in “pages.”
DIRSYNC 1.2.840.113556.1.4.841 Used to find objects that have changed over a period of time.
Server-side Sort
Request
1.2.840.113556.1.4.473 Used to inform the server to sort the results of a search.
Server-side Sort
Response
1.2.840.113556.1.4.474 Returned by the server in response to a sort request.
Show deactivated links 1.2.840.113556.1.4.2065 Used to request deactivated links to be included in a search.
Show deleted objects 1.2.840.113556.1.4.417 Used to request deleted objects to be included in a search.
VLV Request 2.16.840.1.113730.3.4.9 Used to request a virtual list view of results from a search. This control is new
to Windows Server 2003.
VLV Response 2.16.840.1.113730.3.4.10 Response from a server returning a virtual list view of results from a search.
This control is new to Windows Server 2003.
See Also
Recipe 4.8; Recipe 15.8; RFC 2251 (Lightweight Directory Access Protocol [v3]) for a
description of LDAP controls; 3.1.1.3.4.1 LDAP Extended Controls; MSDN: Using
Controls
4.5. Using a Fast or Concurrent Bind
Problem
You want to perform an LDAP bind using a concurrent bind, also known as a fast bind.
Concurrent binds are typically used in situations where you need to authenticate a lot
of users, and either those users do not need to directly access the directory or the di‐
rectory access is done with another account.
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Solution
Using a graphical user interface
1. Open LDP.
2. From the menu, select Connection→Connect.
3. For Server, enter the name of a DC.
4. For Port, enter 389.
5. Click OK.
6. From the menu, select Options→Connection Options.
7. Under Option Name:, select LDAP_OPT_FAST_CONCURRENT_BIND.
8. Click the Set button. Then click the Close button.
9. From the menu, select Connection→Bind.
10. Accept the default and bind as the currently logged on user or select the option to
bind with credentials and then enter the credentials.
11. Click OK.
Discussion
Unlike simple binding, concurrent binding does not generate a security token or de‐
termine a user’s group memberships during the authentication process. It determines
only whether the authenticating user has a valid enabled account and password, which
makes it much faster than a typical bind. This is usually used programmatically for ADenabled applications to improve the speed of AD authentication; it’s not something that
you’ll typically do on the fly. Concurrent binding is implemented as a session option
that is set after you establish a connection to a domain controller, but before any bind
attempts are made. After the option has been set, any bind attempt made with the con‐
nection will be a concurrent bind.
There are a couple of caveats when using concurrent binds. First, you cannot enable
signing or encryption, which means that all data for concurrent binds will be sent over
the network in clear text. Second, because the user’s security token is not generated,
access to the directory is done anonymously and access restrictions are based on the
ANONYMOUS LOGON principal.
It is worth mentioning that there is another type of fast bind that is completely different
from the procedure just described. This fast bind is implemented within ADSI, and it
simply means that when you fast-bind to an object, the objectClass attribute for the
object is not retrieved; therefore, the object-specific IADs class interfaces are not
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available. For example, if you bind to a user object using an ADSI fast bind, then only
the basic IADs interfaces will be available, not the IADsUser interfaces.
This is the complete list of interfaces that are available for objects retrieved with fast
binds:
• IADs
• IADsContainer
• IDirectoryObject
• IDirectorySearch
• IADsPropertyList
• IADsObjectOptions
• ISupportErrorInfo
• IADsDeleteOps
You must use the IADsOpenDSObject::OpenDSObject interface to enable fast binds. If
you call IADsContainer::GetObject on a child object of a parent you used a fast bind
with, the same fast bind behavior applies. Unlike concurrent binds, ADSI fast binds do
not impose any restrictions on the authenticating user. This means that the objectspecific IADs interfaces will not be available. Also, no check is done to verify the object
exists when you call OpenDSObject.
ADSI fast binds are useful when you need to make a lot of updates to objects that you
know exist (perhaps from an ADO query that returned a list of DNs) and you do not
need any IADs-specific interfaces. Instead of two trips over the network per object
binding, there would be only one.
See Also
MSDN: Using Concurrent Binding; MSDN: ADS_AUTHENTICATION_ENUM
4.6. Connecting to an Object GUID
Problem
You want to bind to a container using its globally unique identifier (GUID).
Solution
Using a graphical user interface
1. Open LDP.
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2. From the menu, select Connection→Connect.
3. For Server, enter the name of a domain controller (or leave it blank to do a serverless
bind).
4. For Port, enter 389.
5. Click OK.
6. From the menu, select Connection→Bind.
7. Accept the default and bind as the currently logged on user or select the option to
bind with credentials and then enter the credentials.
8. Click OK.
9. From the menu, select Browse→Search.
10. For BaseDN, enter the GUID of the object that you’re searching for in the following
format:
<GUID=758A39F4A44A0C48A16016457C1AE9E9>
11. For Scope, select the appropriate scope.
12. For Filter, enter an LDAP filter.
13. Click Run.
Discussion
Each object in Active Directory has a GUID associated with it, stored in the object
GUID attribute. The GUID is, for most purposes, a unique identifier that retains its value
even if an object is updated, renamed, or moved. This makes the GUID the preferable
means of binding to an object, rather than hardcoding a reference to an object name
that might change or by using a potentially complex LDAP query.
See Also
“‘GUIDs’ or ‘Having unique in the name doesn’t make it so...’” for a more in-depth
discussion of the objectGUID attribute; MSDN: IADs.GUID; MSDN: Using object‐
GUID to Bind to an Object; Recipe 4.7
4.7. Connecting to a Well-Known GUID
Problem
You want to connect to LDAP using one of the well-known GUIDs in Active Directory.
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Solution
Using a graphical user interface
1. Open LDP.
2. From the menu, select Connection→Connect.
3. For Server, enter the name of a domain controller (or leave it blank to do a serverless
bind).
4. For Port, enter 389.
5. Click OK.
6. From the menu, select Connection→Bind.
7. Accept the default and bind as the currently logged on user or select the option to
bind with credentials and then enter the credentials.
8. Click OK.
9. From the menu, select View→Tree.
10. For the DN, enter:
<WKGUID=<WKGUID>,<DomainDN>>
where <WKGUID> is the well-known GUID that you want to connect to, and
<DomainDN> is the distinguished name of a domain.
11. Click OK. In the lefthand menu, you can now browse the container corresponding
to the well-known GUID that you specified.
Using a command-line interface
To enumerate the well-known GUIDs in the Domain NC, use the following syntax:
> adfind -default -s base wellknownObjects
To display the WKGUIDs in the Configuration NC, replace –default with –config in
the previous syntax.
To connect to a well-known GUID in the Domain NC using AdFind, use the following
syntax:
> adfind -b "<WKGUID=<WKGUID>,<DomainDN>>" -s base -dn
Because of additional security settings attached to the Deleted Objects
container, if you specify the GUID you must also use the –showdel
switch in AdFind.
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Using PowerShell
Get-ADObject (Get-ADRootDSE).DefaultNamingContext -Properties wellKnownObjects↵
| Select wellKnownObjects -ExpandProperty wellknownobjects
Discussion
The Domain NC in Active Directory contains a number of well-known GUIDs that
correspond to containers that exist in every AD implementation. These GUIDs are
stored as wellKnownObjects attributes within the <DomainDN> object, and they allow
administrators and developers to consistently connect to critical containers even if they
are moved or renamed. The <DomainDN> container possesses the following objects that
correspond to well-known GUIDs:
• cn=NTDS Quotas,<DomainDN>
• cn=Microsoft,cn=Program Data,<DomainDN>
• cn=Program Data,<DomainDN>
• cn=ForeignSecurityPrincipals,<DomainDN>
• cn=Deleted Objects,<DomainDN>
• cn=Infrastructure,<DomainDN>
• cn=LostAndFound,<DomainDN>
• cn=System,<DomainDN>
• OU=Domain Controllers,<DomainDN>
• cn=Computers,<DomainDN>
• cn=Users,<DomainDN>
The Configuration NC adds these additional WKGUIDs:
• cn=NTDS Quotas,cn=Configuration,<ForestRootDN>
• cn=LostAndFoundConfig,cn=Configuration,<ForestRootDN>
• cn=Deleted Objects,cn=Configuration,<ForestRootDN>
See Also
MSDN: Binding to Well-Known Objects Using WKGUID
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4.8. Searching for Objects in a Domain
Problem
You want to find objects in a domain that match certain criteria.
Solution
Using a graphical user interface
1. Open LDP.
2. From the menu, select Connection→Connect.
3. For Server, enter the name of a domain controller (or leave it blank to do a serverless
bind).
4. For Port, enter 389.
5. Click OK.
6. From the menu, select Connection→Bind.
7. Accept the default and bind as the currently logged on user or select the option to
bind with credentials and then enter the credentials.
8. Click OK.
9. From the menu, select Browse→Search.
10. For BaseDN, type the base distinguished name where the search will start. (You can
leave this blank if you wish to connect to the Domain NC as the base DN.)
11. For Scope, select the appropriate scope.
12. For Filter, enter an LDAP filter.
13. Click Run.
Using a command-line interface
To run a query using the built-in DSQuery tool, use the following syntax:
> dsquery * <BaseDN> -scope <Scope> -filter "<Filter>" -attr "<AttrList>"
To retrieve the SAM account name for all user objects within the adatum.com domain,
for example, use the following syntax:
> dsquery * dc=adatum,dc=com -filter
"(&(objectclass=user)(objectcategory=person))" -attr sAMAccountName
To run a query using adfind, use the following syntax:
> adfind -b <BaseDN> -s <Scope> -f <Filter> <Attributes>
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Querying for SAM account names of user objects with adfind takes the following
syntax:
> adfind -b dc=adatum,dc=com -f↵
"(&(objectclass=user)(objectcategory=person))" sAMAccountName
Both DSQuery and AdFind assume a default search scope of subtrees;
you need only to specify the search scope if you want to use a different
one.
Using PowerShell
The following example will search for user objects within the current Active Directory
domain:
Get-ADObject -Filter {(objectClass -eq "user") -and ↵
(objectCategory -eq "person")}
Discussion
Most tools that can be used to search Active Directory require a basic understanding of
how to perform LDAP searches using a base DN, search scope, and search filter, as
described in RFC 2251 and RFC 2254. The base DN is where the search begins in the
directory tree. The search scope defines how far down in the tree to search from the
base DN. The search filter is a prefix notation string that contains equality comparisons
of attribute and value pairs.
The scope can be base, onelevel (or one), or subtree (or sub). A base scope will match
only the base DN, onelevel will match only objects that are contained directly under
the base DN, and subtree will match everything from the base DN and any objects
beneath it.
There are no LDAP query scopes that will walk backward “up” the tree.
The search filter syntax is a powerful way to represent simple and complex queries. For
example, a filter that matches all of the user objects would be (&(objectclass=user)
(objectcategory=Person)). For more information on filters, see RFC 2254.
Using a graphical user interface
To customize the list of attributes returned for each matching object, look at the GUI
discussion in Recipe 4.2.
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Using a command-line interface
<AttrList> should be a space-separated list of attributes to return. To return all at‐
tributes that have been populated with a value, leave this field blank or use an asterisk (*).
See Also
Recipe 4.2 for viewing attributes of objects; Recipe 4.9 for setting advanced ADO op‐
tions; RFC 2251 (Lightweight Directory Access Protocol [v3]); RFC 2254 (Lightweight
Directory Access Protocol [v3]); “LDAP Query Basics”
4.9. Searching the Global Catalog
Problem
You want to perform a forest-wide search using the global catalog.
Solution
Using a graphical user interface
1. Open LDP.
2. From the menu, select Connection→Connect.
3. For Server, enter the name of a global catalog server.
4. For Port, enter 3268.
5. Click OK.
6. From the menu, select Connection→Bind.
7. Accept the default and bind as the currently logged on user or select the option to
bind with credentials and then enter the credentials.
8. Click OK.
9. From the menu, select Browse→Search.
10. For BaseDN, type the base distinguished name of where to start the search.
11. For Scope, select the appropriate scope.
12. For Filter, enter an LDAP filter.
13. Click Run.
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Using a command-line interface
To query the global catalog using DSQuery, use the following syntax:
> dsquery * <BaseDN> -gc -scope <Scope> -filter "<Filter>" -attr "<AttrList>"
To run a query using AdFind, use the following syntax:
> adfind -gc -b <BaseDN> -s <Scope> -f <Filter> <Attributes>
Using PowerShell
To query the global catalog server named dc1.adatum.com for all computer objects in
the adatum.com domain, run the following command:
Get-ADObject -Filter {ObjectClass -eq "computer"} -Server dc1.adatum.com:3268↵
-SearchBase "dc=adatum,dc=com" -Properties Name | FT Name
Discussion
The global catalog facilitates forest-wide searches. When you perform a normal LDAP
search over port 389, you are searching against a particular partition within Active
Directory, whether that is the Domain naming context, Configuration naming context,
Schema naming context, or an application partition. If you have multiple domains in
your forest, this type of search will not search against all domains; it will search only
the domain that you specify.
The global catalog, by contrast, contains a subset of the attributes for all objects in the
forest (excluding objects in application partitions). Think of it as a subset of all the
naming contexts combined. Every object in the directory will be contained in the global
catalog (except for objects contained within application partitions), but only some of
the attributes of those objects will be available. For that reason, if you perform a global
catalog search and do not get values for attributes you were expecting to, make sure
those attributes are included in the global catalog, also known as the partial attribute
set (PAS). See Recipe 10.13 for more information on adding information to the PAS. As
an alternative, you can query a DC within the domain containing the object to return
a list of all attributes configured for that object. Note that the Active Directory Admin‐
istrative Center provides a method to easily change the scope of a search to be a global
catalog search.
Using a graphical user interface
The only difference between this solution and the one in Recipe 4.8 is that the port has
changed to 3268, which is the standard GC port.
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Using a command-line interface
The only difference between this solution and the one in Recipe 4.8, both for DSQuery
and AdFind, is the addition of the -gc flag.
See Also
Recipe 4.8 for searching for objects; Recipe 10.13
4.10. Searching for a Large Number of Objects
Problem
Your search is returning exactly 1,000 objects, which is only a subset of the objects you
expected, and you want it to return all matching objects.
Solution
You might notice, when using some tools, that searches with large numbers of matches
stop displaying after 1,000. By default, domain controllers return a maximum of 1,000
entries from a search unless paging is enabled. This is done to prevent queries from
consuming excessive resources on domain controllers by retrieving the results all at
once instead of in pages or batches. The following examples are variations of
Recipe 4.8, which will show how to enable paging and return all matching entries.
Using a graphical user interface
1. Open LDP.
2. From the menu, select Connection→Connect.
3. For Server, enter the name of a domain controller (or leave it blank to do a serverless
bind).
4. For Port, enter 389.
5. Click OK.
6. From the menu, select Connection→Bind.
7. Accept the default and bind as the currently logged on user or select the option to
bind with credentials and then enter the credentials.
8. Click OK.
9. From the menu, select Browse→Search.
10. For BaseDN, type the base distinguished name of where the search will start. (You
can leave this blank if you wish to connect to the domain NC as the base DN.)
11. For Scope, select the appropriate scope.
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12. For Filter, enter an LDAP filter.
13. Click Options to customize the options for this query.
14. For “Time limit,” enter a value such as 120.
15. For “Size limit,” enter the number of objects to be returned with each page (e.g.,
1,000).
16. Under Search Call Type, select Paged.
17. Click OK and then Run to perform the query. A page of results (i.e., 1,000 entries)
will be displayed each time you click Run until all results have been returned.
Using a command-line interface
> dsquery * <BaseDN> -limit 0 -scope <Scope> -filter "<Filter>" ↵
-attr "<AttrList>"
Using PowerShell
The following PowerShell command will search the default Users container and return
all objects while limiting results to 12,000 objects:
Get-ADObject -SearchBase "cn=users,dc=adatum,dc=com" -Filter * -ResultSetSize ↵
12000
Discussion
Paged searching support is implemented via an LDAP control. LDAP controls were
defined in RFC 2251 and the Paged control in RFC 2696. Controls are extensions to
LDAP that were not built into the protocol, so not all directory vendors support the
same ones.
In Active Directory, you can change the default maximum page size of
1,000 by modifying the LDAP query policy. See Recipe 4.27 for more
information.
Active Directory will return a maximum of 256 KB of data even when paged searching
is enabled. This value is defined in the LDAP query policy and can be modified like the
maximum page size (see Recipe 4.27).
Using a graphical user interface
A word of caution when using LDP to display a large number of entries: by default, only
2,048 lines will be displayed in the right pane. To change that value, go to Op‐
tions→General and change the number of lines under Buffer Size to a larger number.
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Note that newer tools aren’t as limited as some of the tools that have been around a long
time. For example, the Active Directory Administrative Center displays up to 20,000
objects in a search by default.
Using a command-line interface
The only difference between this solution and the one in Recipe 4.8 is the addition of
the -limit 0 flag. With -limit set to 0, paging will be enabled according to the default
LDAP query policy; matching objects will be returned within those parameters. If
-limit is not specified, a maximum of 100 entries will be returned.
AdFind enables paged searches by default; it will return any number of
objects from a query without any modification.
See Also
Recipe 4.8 for searching for objects; Recipe 4.27 for viewing the default LDAP policy;
RFC 2251 (Lightweight Directory Access Protocol [v3]); RFC 2696 (LDAP Control
Extension for Simple Paged Results Manipulation)
4.11. Searching with an Attribute-Scoped Query
Problem
You want to perform a search using an individual value within a multivalued attribute
as part of the search criteria. An attribute-scoped query can do this in a single query,
instead of the previous method, which required multiple queries.
Solution
Using a graphical user interface
1. Follow the steps in Recipe 4.4 to enable an LDAP control.
2. Select the Attribute Scoped Query control.
3. For Value, enter the multivalued attribute name (e.g., member).
4. Click the “Check in” button.
5. Click OK.
6. From the menu, select Browse→Search.
7. For BaseDN, type the DN of the object that contains the multivalued attributes.
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8. For Scope, select Base.
9. For Filter, enter an LDAP filter to match against the objects that are part of the
multivalued DN attribute.
10. Click Run.
Attribute-scoped queries can only be performed using a Base scope.
Using a command-line interface
AdFind allows attribute-scoped queries by using the -asq switch. For example:
adfind -b cn=somegroup,cn=users,dc=domain,dc=group -asq member ↵
-f objectclass=user
samaccountname
Using PowerShell
The PowerShell pipeline will allow you to perform an attribute-scoped query as follows:
Get-ADGroup "Domain Admins" | Get-ADGroupMember |↵
Get-ADUser -Properties sAMAccountName | Select samaccountname
Discussion
When dealing with group objects, you may have encountered the problem where you
wanted to search against the members of a group to find a subset or to retrieve certain
attributes about each member. This normally involved performing a query to retrieve
all of the members, and additional queries to retrieve whatever attributes you needed
for each member. This was less than ideal, so an alternative was developed.
With an attribute-scoped query, you can perform a single query against the group object
and return whatever properties you need from the member’s object, or return only a
subset of the members based on certain criteria. Let’s look at the LDAP search param‐
eters for an attribute-scoped query:
Attribute-scoped query control value
The value to set for this control should be the DN attribute that you want to iterate
over (for example, member).
Base DN
This must be the DN of the object that contains the DN attribute (e.g., cn=Domain
Admins,cn=users,dc=adatum,dc=com).
Scope
This must be set to Base to query only the group object itself.
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Filter
The filter will match against objects defined in the Control Value. For example, a
filter of (objectClass=computer) would match computer objects only. You can
also use any other attributes that are available with those objects. The following
filter would match all computer objects that have a Description attribute equal to
“Sales”:
(&(objectclass=computer)(Description=Sales))
Attributes
This should contain the list of attributes to return for the objects matched in the
DN attribute.
When performing an attribute-scoped query against a member attribute, it’s important
to remember that primary group membership is handled as a special case; as such you
may experience unpredictable results in this situation.
See Also
Recipe 4.4; MSDN: Performing an Attribute Scoped Query
4.12. Searching with a Bitwise Filter
Problem
You want to search against an attribute that contains a bit flag, which requires you to
use a bitwise filter to perform the search.
Solution
Using a graphical user interface
1. Open LDP.
2. From the menu, select Connection→Connect.
3. For Server, enter the name of a domain controller (or leave it blank to do a serverless
bind).
4. For Port, enter 389.
5. Click OK.
6. From the menu, select Connection→Bind.
7. Accept the default and bind as the currently logged on user or select the option to
bind with credentials and then enter the credentials.
8. Click OK.
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9. From the menu, select Browse→Search.
10. For Base DN, type the base distinguished name of where the search will start. (You
can leave this blank if you wish to connect to the domain NC as the base DN.)
11. For Scope, select the appropriate scope.
12. For the Filter, enter the bitwise expression, such as the following, which will find
all universal groups:
(&(objectCategory=group)(groupType:1.2.840.113556.1.4.804:=8))
13. Click Run.
Using a command-line interface
The following query finds universal groups in the adatum.com domain by using a bit‐
wise AND filter:
> dsquery * dc=adatum,dc=com -scope subtree -attr "name" -filter↵
"(&(objectclass=group)(objectCategory=group)↵
(groupType:1.2.840.113556.1.4.804:=8) )"
The following query finds disabled user accounts in the adatum.com domain by using
a bitwise AND filter:
> dsquery * dc=adatum,dc=com -attr name -scope subtree -filter
"(&(objectclass=user)(objectcategory=person)↵
(useraccountcontrol:1.2.840.113556.1.4.
803:=2))"
You can also perform queries that use bitwise filters using AdFind. The following will
find all disabled user accounts in the adatum.com domain:
> adfind -default -bit -f useraccountcontrol:AND:=2
Similarly, the following will return all universal groups in the adatum.com domain using
a bitwise filter:
> adfind -default -bit -f groupType:AND:=8
Using PowerShell
The following command will find all universal groups in the current domain:
Get-ADObject -LDAPFilter {(groupType:1.2.840.113556.1.4.803:=8)} | Select Name
Discussion
Many attributes in Active Directory are composed of bit flags. A bit flag is often used
to encode properties about an object into a single attribute. For example, the group
Type attribute on group objects is a bit flag that is used to determine the group scope
and type.
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The userAccountControl attribute on user and computer objects is used to describe a
whole series of properties, including account status (i.e., enabled or disabled), account
lockout, password not required, smartcard authentication required, and so on.
The searchFlags and systemFlags attributes on attributeSchema objects define,
among other things, whether an attribute is constructed, indexed, and included as part
of Ambiguous Name Resolution (ANR).
To search against these types of attributes, you need to use bitwise search filters. There
are two types of bitwise search filters you can use, one that represents a logical OR and
one that represents a logical AND. This is implemented within a search filter as a
matching rule. A matching rule is simply a way to inform the LDAP server (in this case,
a domain controller) to treat part of the filter differently. Here is an example of what a
matching rule looks like:
(userAccountControl:1.2.840.113556.1.4.803:=514)
The format is (attributename:MatchingRuleOID:=value), though AdFind allows you
to use an easier syntax for bitwise queries. As mentioned, there are two bitwise matching
rules, which are defined by OIDs. The logical AND matching rule OID is
1.2.840.113556.1.4.803, and the logical OR matching rule OID is 1.2.840.113556.1.4.804.
These OIDs instruct the server to perform special processing on the filter. A logical OR
filter will return success if any bit specified by value is stored in attributename. Al‐
ternatively, the logical AND filter will return success if all bits specified by value match
the value of attributename. Perhaps an example will help clarify this.
To create a normal user account, you have to set userAccountControl to 514. The
number 514 was calculated by adding the normal user account flag of 512 together with
the disabled account flag of 2 (512 + 2 = 514). If you use the following logical OR
matching rule against the 514 value, as shown here:
(useraccountcontrol:1.2.840.113556.1.4.804:=514)
then all normal user accounts (flag 512) OR disabled accounts (flag 2) would be re‐
turned. This would include enabled user accounts (from flag 512), disabled computer
accounts (from flag 2), and disabled user accounts (from flag 2). In the case of userAc
countControl, flag 2 can apply to both user and computer accounts, which is why both
would be included in the returned entries.
One of the benefits of bitwise matching rules is that they allow you to combine a bunch
of comparisons into a single filter. In fact, it may help to think that the OR filter could
also be written using two expressions:
(|(useraccountcontrol:1.2.840.113556.1.4.804:=2)
(useraccountcontrol:1.2.840.113556.1.4.804:=512))
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Just as before, this will match userAccountControl attributes that contain either the 2
or 512 flag; we’re performing two OR operations against the same value, first ORing the
value against 2, then against 512.
For the logical AND operator, similar principles apply. Instead of any of the bits in the
flag being a possible match, all of the bits in the flag must match for it to return a success.
If the userAccountControl example was changed to use logical AND, it would look like
this:
(useraccountcontrol:1.2.840.113556.1.4.803:=514)
In this case, only normal user accounts that are also disabled would be returned. The
same filter could be rewritten using the & operator instead of | as in the following:
(&(useraccountcontrol:1.2.840.113556.1.4.803:=2)
(useraccountcontrol:1.2.840.113556.1.4.803:=512))
An important subtlety to note is that when you are comparing only a single bit-flag
value, the logical OR and logical AND matching rules would return the same result. So,
if you wanted to find any normal user accounts, you could search on the single bit flag
of 512 using either of the following:
(useraccountcontrol:1.2.840.113556.1.4.803:=512)
(useraccountcontrol:1.2.840.113556.1.4.804:=512)
Using PowerShell
Searching on a bitwise operator in PowerShell is done using the appropriate LDAP filter,
as you can see. In other chapters we will look at individual AD cmdlets that mask the
bitwise search into a more human-readable operation, such as the Enable-ADAccount
and Disable-ADAccount cmdlets.
See Also
MSDN: Enumerating Groups by Scope or Type in a Domain; MSDN: Determining
Which Properties Are Non-Replicated, Constructed, Global Catalog, and Indexed; MS
KB 305144 (How to Use the UserAccountControl Flags to Manipulate User Account
Properties)
4.13. Creating an Object
Problem
You want to create an object.
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Solution
In each solution in this recipe, an example of adding a user object is shown. Modify the
examples as needed to include whatever class and attributes you need to create.
Using a graphical user interface
1. Open ADSI Edit.
2. If an entry for the naming context you want to browse is not already displayed, do
the following:
a. Right-click on ADSI Edit in the right pane and click “Connect to.”
b. Fill in the information for the naming context, container, or OU you want to
add an object to. Click on the Advanced button if you need to enter alternate
credentials.
3. In the left pane, browse to the container or OU you want to add the object to. Once
you’ve found the parent container, right-click on it and select New→Object.
4. Under Select a Class, select user.
5. For the cn, enter jsmith and click Next.
6. For sAMAccountName, enter jsmith and click Next.
7. Click the More Attributes button to enter additional attributes.
8. Click Finish.
Using a command-line interface
Create an LDAP Data Interchange Format (LDIF) file called create_object.ldf with the
following contents:
dn: cn=jsmith,cn=users,dc=adatum,dc=com
changetype: add
objectClass: user
samaccountname: jsmith
Then run the following command:
> ldifde -v -i -f create_object.ldf
It is also worth noting that you can add a limited number of object types with the dsadd
command. Run dsadd /? from a command line for more details.
You can also create objects using AdMod; to create a new user object in the ada‐
tum.com domain use the following syntax:
> admod -b "cn=Joe Smith,cn=users,dc=adatum,dc=com"↵
objectclass::user samaccountname::jsmith -add
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Using PowerShell
To create a new computer object named Kiosk2 in the Workstations OU, use the fol‐
lowing PowerShell command:
New-ADObject -Path "OU=Workstations,dc=adatum,dc=com" -Type Computer ↵
-Name "Kiosk2" -Description "Computer in lobby" -OtherAttributes ↵
@{SamAccountName="Kiosk2"}
Discussion
To create an object in Active Directory, you have to specify the objectClass, RDN value,
and any other mandatory attributes that are not automatically set by Active Directory.
Some of the automatically generated attributes include objectGUID, instanceType, and
objectCategory.
In the jsmith example, the object class was user, the RDN value was jsmith, and the
only other attribute set was sAMAccountName. Admittedly, this user object is unusable
in its current state because it will be disabled by default and no password was set, but it
should give you an idea of how to create an object. In the case of a user object, you’ll
need to configure a password that meets any existing password complexity requirements
before enabling the user.
Using a graphical user interface
Other tools, such as Active Directory Administrative Center and AD Users and Com‐
puters, could be used to do the same thing, but ADSI Edit is useful as a generic object
editor.
One attribute that you will not be able to set via ADSI Edit is the password (unico
dePwd attribute). It is stored in binary form and needs to be edited using a secure con‐
nection. If you want to set the password for a user through a GUI, you can do it with
the AD Users and Computers snap-in or Active Directory Administrative Center.
Using a command-line interface
For more on ldifde, see Recipe 4.28.
With DSAdd, you can set numerous attributes when creating an object. The downside
is that you can create only the following object types: computer, contact, group, OU,
quota, and user.
See Also
Recipe 4.28; Recipe 4.29 for importing objects with LDIF; MSDN: IADsContainer::
GetObject; MSDN: IADsContainer::Create; MSDN: IADs::Put; MSDN: IADs::SetInfo
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4.14. Modifying an Object
Problem
You want to modify one or more attributes of an object.
Solution
The following example sets the employeeID attribute for a user object.
Using a graphical user interface
1. Open Active Directory Administrative Center.
2. In the bottom-right pane, enter the search criteria of the desired object and then
click the Search button.
3. In the search results, locate the object, right-click it, and then click Properties.
4. Scroll down to the Extensions section and then click the Attribute Editor tab.
5. Scroll down and click the employeeID attribute and then click the Edit button.
6. Enter the value and then click OK.
7. Click OK again to close the object properties.
Using a command-line interface
Create an LDIF file called modify_object.ldf with the following contents:
dn: cn=jsmith,cn=users,dc=adatum,dc=com
changetype: modify
replace: employeeID
employeeID: 17320
-
Then run the following command:
> ldifde -v -i -f modify_object.ldf
To modify an object using AdMod, you’ll use the following general syntax:
> admod -b <ObjectDN> <attribute>:<operation>:<value>
For example, you can add a description to a user object using the following syntax:
> admod -b cn="Joe Smith,cn=Users,dc=adatum,dc=com" description::Consultant
You can modify a limited number of object types with the dsmod command. Run
dsmod /? from a command line for more details.
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Using PowerShell
To modify an object using PowerShell, use the following syntax:
Set-ADObject -Identity <"ObjectDN"> -Replace @{<property>=<"value">}
Discussion
Using a command-line interface
For more on ldifde, see Recipe 4.28.
As of the publication of this book, the only types of objects you can modify with DSMod
are the following: computer, contact, group, OU, server, quota, partition, and user.
As you saw in this recipe, the basic format of the AdMod command when used to modify
an attribute is as follows:
> admod -b <ObjectDN> <attribute>:<operation>:<value>
The value used for <operation> can be any one of the following:
<blank>
Updates the attribute with the new value. (In practical terms, this leads to a syntax
of <attribute>::<value>, with nothing included between the two colons.)
+
Adds a value to an attribute.
−
Clears an attribute.
++
Adds multiple values to an attribute.
−−
Removes multiple values from an attribute.
To change a user’s password via AdMod, encrypt the connection by
using the -kerbenc switch and then modify the unicodepwd attribute.
See Also
MSDN: IADs::Put; MSDN: IADs::PutEx; MSDN: IADs::SetInfo; MSDN: ADS_ PROP‐
ERTY_OPERATION_ENUM
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4.15. Modifying a Bit-Flag Attribute
Problem
You want to safely modify an attribute that contains a bit flag, without blindly over‐
writing its existing contents. The solutions in this recipe modify a new attribute named
adatum-UserProperties that was previously added to the schema.
Solution
Using VBScript
' This code safely modifies a bit flag attribute
' ------ SCRIPT CONFIGURATION ------
strObject = "<ObjectDN>" ' e.g. cn=jsmith,cn=users,dc=adatum,dc=com
strAttr = "<AttrName>" ' e.g. adatum-UserProperties
boolEnableBit = <TRUEorFALSE> ' e.g. FALSE
intBit = <BitValue> ' e.g. 16
' ------ END CONFIGURATION --------
set objObject = GetObject("LDAP://" & strObject)
intBitsOrig = objObject.Get(strAttr)
intBitsCalc = CalcBit(intBitsOrig, intBit, boolEnableBit)
if intBitsOrig <> intBitsCalc then
objObject.Put strAttr, intBitsCalc
objObject.SetInfo
WScript.Echo "Changed " & strAttr & " from " & intBitsOrig &↵
" to " & intBitsCalc
else
WScript.Echo "Did not need to change " & strAttr & " (" & intBitsOrig & ")"
end if
Function CalcBit(intValue, intBit, boolEnable)
CalcBit = intValue
if boolEnable = TRUE then
CalcBit = intValue Or intBit
else
if intValue And intBit then
CalcBit = intValue Xor intBit
end if
end if
End Function
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Using PowerShell
To set the adatum-UserProperties value using PowerShell, use the following example
script:
$user = Get-ADObject "cn=jsmith,cn=users,dc=adatum,dc=com"↵
-Properties adatum-UserProperties
if (!$user.adatum-UserProperties) {
Set-ADObject $user -Add @{"adatum-UserProperties"=4}
Write-Host "Changed from NULL to 4."
} else {
$value = $user.adatum-UserProperties + 4
Set-ADObject $user -Replace @{"adatum-UserProperties"=$value}
Write-Host "Changed value from" $user.adatum-UserProperties "to" $value"."
}
Discussion
Recipe 4.12 described how to search against attributes that contain a bit flag, which is
used to encode various settings about an object in a single attribute. As a quick recap,
you need to use a logical OR operation to match any bits being searched against, and a
logical AND to match a specific set of bits. If you want to set an attribute that is a bit
flag, you need to take special precautions to ensure that you don’t overwrite an existing
bit. Let’s consider an example. Adatum wants to secretly store some politically incorrect
information about their users, such as whether the user is really old or has big feet. They
don’t want to create attributes such as adatum-UserHasBigFeet, so they decide to encode
the properties in a single bit-flag attribute. They decide to call the attribute adatumUserProperties with the possible bit values shown in Table 4-3.
Table 4-3. Sample bit-flag attribute values
Value Description
1 User is overweight.
2 User is very tall.
4 User has big feet.
8 User is very old.
After they extend the schema to include the new attribute, Adatum needs to initially
populate the attribute for all their users. To do so they can simply logically OR the values
together that apply to each user. So, if settings 4 and 8 apply to the jsmith user, his
adatum-UserProperties would be set to 12 (4 OR 8). No big deal so far. The issue comes
in when they need to modify the attribute in the future.
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You will, however, find that searching for information based on a bitflag attribute is not terribly efficient. This is because bit flags cannot be
indexed; you need to calculate the value for every object populated with
the bit-flag attribute in question.
They later find out that jsmith was a former basketball player and is 6′8″. They need to
set the 2 bit (for being tall) in his adatum-UserProperties attribute. To set the 2 bit they
need to first determine whether it has already been set. If it has already been set, then
there is nothing to do. If the 2 bit hasn’t been set, they need to logical OR 2 with the
existing value of jsmith’s adatum-UserProperties attribute. If they simply set the at‐
tribute to 2, it would overwrite the 4 and 8 bits that had been set previously. In the
VBScript solution, they could use the CalcBit function to determine the new value:
intBitsCalc = CalcBit(intBitsOrig, 2, TRUE)
The result would be 14 (12 OR 2).
The same logic applies if they want to remove a bit, except the XOR logical operator is
used.
Active Directory contains numerous bit-flag attributes, most notably
options (which is used on several different object classes) and userAc
countControl (which is used on user objects). We do not recommend
blindly setting those attributes unless you know what you are doing. It
is preferable to use a script from this recipe so that it calculates the new
value based on the existing value.
You should note that it’s certainly possible to modify bitwise attributes using a GUI tool
like ADSI Edit or a command-line tool like DSMod. However, it will require a certain
amount of manual effort, as you’ll first need to make note of the existing attribute value
and then calculate the new value using a calculator or some other method. The VBScript
solution presented here simply automates that process by performing the lookup and
calculations for you.
Using PowerShell
The PowerShell solution looks at the existing adatum-UserProperties attribute value.
If it is null, it changes it to 4. If it contains a value already, it takes that value and adds 4
to it, and then replaces the existing value with the new value.
See Also
Recipe 4.12 for searching with a bitwise filter
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4.16. Dynamically Linking an Auxiliary Class
Problem
You want to dynamically link an auxiliary class to an existing object instance.
Solution
In each solution in this recipe, an example of adding the custom adatum-SalesUser
auxiliary class to the jsmith user object will be described.
Using a graphical user interface
1. Open ADSI Edit.
2. If an entry for the naming context you want to browse is not already displayed, do
the following:
a. Right-click on ADSI Edit in the right pane and click “Connect to.”
b. Fill in the information for the naming context, container, or OU you want to
add an object to. Click the Advanced button if you need to enter alternate cre‐
dentials.
3. In the left pane, browse to the container or OU that contains the object you want
to modify. Once you’ve found the object, right-click on it and select Properties.
4. Edit the values for the objectClass attribute.
5. For “Value to add,” enter adatum-SalesUser.
6. Click Add.
7. Click OK twice.
Using a command-line interface
Create an LDIF file called dynamically_link_class.ldf with the following contents:
dn: cn=jsmith,cn=users,dc=adatum,dc=com
changetype: modify
add: objectClass
objectClass: adatum-SalesUser
-
Then run the following command:
> ldifde -v -i -f dynamically_link_class.ldf
Alternatively, you can use AdMod as follows:
> admod -b <ObjectDN> objectClass:+:<Dynamic Object Class>
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Using PowerShell
Set-ADObject -Identity "cn=jsmith,cn=users,dc=adatum,dc=com"↵
-Add @{ObjectClass="adatum-SalesUser"}
Discussion
Dynamically linking an auxiliary class to an object is an easy way to use new attributes
without modifying the existing object class definition in the schema.
A situation in which it makes more sense to dynamically link auxiliary classes than to
link them statically is when several organizations or divisions within a company main‐
tain their own user objects and want to add new attributes to the user class.
It is also worth mentioning that extensive use of dynamically linked auxiliary classes
can lead to problems. If several groups are using different auxiliary classes, it might
become hard to determine what attributes you can expect on your user objects. Essen‐
tially, you could end up with many variations of a user class that each group has imple‐
mented through the use of dynamic auxiliary classes. For this reason, use of dynamic
auxiliary classes should be closely monitored. In addition, some tools that access Active
Directory may not work properly with auxiliary classes.
See Also
Recipe 4.14 for modifying an object
4.17. Creating a Dynamic Object
Problem
You want to create an object that is automatically expired and removed from the direc‐
tory after a period of time.
Solution
Using a graphical user interface
1. Open LDP.
2. Click Connection→Connect and click OK.
3. Click Connection→Bind.
4. Accept the default and bind as the currently logged on user or select the option to
bind with credentials and then enter the credentials.
5. Click View→Tree. Enter the DN of the parent container of the object you want to
create and then click OK.
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6. Click Browse→Add Child. The Add window will appear.
7. In the DN text box, enter the DN of the new object.
8. In the Attribute text box, enter objectClass. In the Values text box, enter the object
class of the object you are creating, such as 'user'. Click Enter. In the Values text
box, type dynamicObject and click Enter.
9. In the Attribute text box, type entryTTL. In the Values text box, enter the time to
live (TTL) of the object you are creating, such as '3600'. Click Enter.
10. Enter any other attributes and values that you wish to populate in the Attribute and
Values text boxes.
11. Click Run.
Using a command-line interface
Create an LDIF file called create_dynamic_object.ldf with the following contents:
dn: cn=jsmith,cn=users,dc=adatum,dc=com
changetype: add
objectClass: user
objectClass: dynamicObject
entryTTL: 1800
sAMAccountName: jsmith
Then run the following command:
> ldifde -v -i -f create_dynamic_object.ldf
Discussion
The ability to create dynamic objects allows you to create objects that have a limited
lifespan before they are automatically removed from the directory. To create a dynamic
object, you simply need to specify the objectClass to have a value of dynamicObject
in addition to its structural objectClass (e.g., user) value when instantiating the object.
The entryTTL attribute can also be set to the number of seconds before the object is
automatically deleted. If entryTTL is not set, the object will use the dynamicObjectDe
faultTTL attribute specified in the domain. The entryTTL cannot be lower than the
dynamicObjectMinTTL for the domain. See Recipe 4.19 for more information on how
to view and modify these default values.
Dynamic objects have a few special properties worth noting:
• A static object cannot be turned into a dynamic object. The object must be marked
as dynamic when it is created.
• Dynamic objects cannot be created in the Configuration NC and Schema NC.
• Dynamic objects do not leave behind tombstone objects.
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• Dynamic objects that are containers cannot have static child objects.
• A dynamic container will not expire prior to any child objects contained within it.
If the dynamic container has a lower TTL value than any of the children, once the
container’s TTL expires it will be reset to the highest TTL value of the children plus
one second.
See Also
Recipe 4.18 for refreshing a dynamic object; Recipe 4.19 for modifying the default dy‐
namic object properties
4.18. Refreshing a Dynamic Object
Problem
You want to refresh a dynamic object to keep it from expiring and getting deleted from
Active Directory.
Solution
In each solution in this recipe, an example of adding a user object is used. Modify the
examples as needed to refresh whatever object is needed.
Using a graphical user interface
1. Open LDP.
2. From the menu, select Connection→Connect.
3. For Server, enter the name of a domain controller (or leave it blank to do a serverless
bind).
4. For Port, enter 389.
5. Click OK.
6. From the menu, select Connection→Bind.
7. Accept the default and bind as the currently logged on user or select the option to
bind with credentials and then enter the credentials.
8. Click OK.
9. Select Browse→Modify.
10. For DN, enter the DN of the dynamic object you want to refresh.
11. For Attribute, enter entryTTL.
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12. For Values, enter the new time to live (TTL) for the object in seconds.
13. Under Operation, select Replace.
14. Click Enter.
15. Click Run.
Using a command-line interface
Create an LDIF file called refresh_dynamic_object.ldf with the following contents:
dn: cn=jsmith,cn=users,dc=adatum,dc=com
changetype: modify
replace: entryTTL
entryTTL: 1800
-
Then run the following command:
> ldifde -v -i -f refresh_dynamic_object.ldf
You can also use AdMod with the following syntax:
> admod -b <ObjectDN> entryTTL::<TTL in Seconds>
Using PowerShell
To refresh a dynamic object using PowerShell, use the following command:
Set-ADObject -Identity "cn=jsmith,cn=users,dc=adatum,dc=com"↵
-Replace @{entryTTL="1800"}
Discussion
Dynamic objects expire after their TTL becomes 0. You can determine when a dynamic
object will expire by looking at the current value of an object’s entryTTL attribute or by
querying msDS-Entry-Time-To-Die, which contains the seconds remaining until expi‐
ration. If you’ve created a dynamic object and need to refresh it so that it will not get
deleted, you must reset the entryTTL attribute to a new value. There is no limit to the
number of times you can refresh a dynamic object. As long as the entryTTL value does
not reach 0, the object will remain in Active Directory.
See Also
Recipe 4.14 for modifying an object; “Dynamic Objects (Windows)”; Recipe 4.17 for
creating a dynamic object
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4.19. Modifying the Default TTL Settings for
Dynamic Objects
Problem
You want to modify the minimum and default TTLs for dynamic objects.
Solution
In each solution in this recipe, we’ll show how to set the DynamicObjectDefaultTTL
setting to 172800. Modifying the DynamicObjectMinTTL can be done in the same
manner.
Using a graphical user interface
1. Open ADSI Edit.
2. If an entry for the Configuration naming context is not already displayed, do the
following:
a. Right-click on ADSI Edit in the right pane and click “Connect to.”
b. Fill in the information for the naming context for your forest. Click on the Ad‐
vanced button if you need to enter alternate credentials.
3. In the left pane, browse to the following path under the Configuration naming
context: Services→Windows NT→Directory Service.
4. Right-click cn=Directory Service and select Properties.
5. Edit the msDS-Other-Settings attribute.
6. Click on DynamicObjectDefaultTTL= <xxxxx> and click Remove.
7. The attribute/value pair should have been populated in the “Value to add” field.
8. Edit the number part of the value to be 172800.
9. Click Add.
10. Click OK twice.
Using a command-line interface
The following ntdsutil command connects to <DomainControllerName>, displays the
current values for the dynamic object TTL settings, sets the DynamicObjectDe
faultTTL to 172800, commits the change, and displays the results:
> ntdsutil "config settings" connections "connect to server↵
<DomainControllerName>" q "show values" "set DynamicObjectDefaultTTL to 172800"↵
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"commit changes"
"show values" q q
Discussion
Two configuration settings apply to dynamic objects:
dynamicObjectDefaultTTL
Defines the default TTL that is set for a dynamic object at creation time unless
another one is set via entryTTL
dynamicObjectMinTTL
Defines the smallest TTL that can be configured for a dynamic object
Unfortunately, these two settings are not stored as discrete attributes. Instead, they are
stored as attribute value assertions (AVAs) in the msDS-Other-Settings attribute on
the cn=DirectoryServices,cn=WindowsNT,cn=Configuration,<ForestRootDN> ob‐
ject. AVAs are used occasionally in Active Directory on multivalued attributes, in which
the values take the form of Setting1=Value1,Setting2=Value2, and so on.
For this reason, you cannot simply manipulate AVA attributes as you would another
attribute. You have to be sure to add or replace values with the same format, as they
existed previously.
Using a command-line interface
You can use ntdsutil in interactive mode or in single-command mode. In this solution,
we’ve included all the necessary commands on a single line. You can, of course, step
through each command by simply running ntdsutil in interactive mode and entering
each command one by one.
See Also
Recipe 4.14 for modifying an object; MSDN: Regular Expression (RegExp) Object
4.20. Moving an Object to a Different OU or Container
Problem
You want to move an object to a different container or OU.
Solution
Using a graphical user interface
1. Open Active Directory Administrative Center.
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2. In the bottom-right pane, enter the search criteria of the desired object and then
click the Search button.
3. In the search results, locate the object, right-click it, and then click Move.
4. In the dialog box, browse to the destination container, click to highlight it, and then
click OK to move the object.
You can also move objects by using the ADSI Edit tool or the Active
Directory Users and Computers snap-in.
Using a command-line interface
To move an object to a new parent container within the same domain, you can use either
dsmove or admod, as follows:
> dsmove "<ObjectDN>" -newparent "<NewParentDN>"
or:
> admod -b <ObjectDN> -move "<NewParentDN>"
Using PowerShell
To move an Active Directory object using PowerShell, use the following syntax:
Move-ADObject -Identity <ObjectDN> -TargetPath <NewParentDN>
Discussion
Using a command-line interface
The DSMove utility can work against any type of object (it has no limitations, as with
DSAdd and DSMod). The first parameter is the DN of the object to be moved. The
second parameter is the new parent container of the object. The -s parameter can ad‐
ditionally be used to designate a specific server to work against.
Regardless of the method you use to move objects, you need to ensure
that the user who is performing the move has the appropriate permis‐
sions to create objects in the destination container and delete objects
from the source container.
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See Also
Recipe 4.23; MSDN: IADsContainer::MoveHere
4.21. Moving an Object to a Different Domain
Problem
You want to move an object to a different domain.
Solution
Using a graphical user interface (ADMT 3.2)
To migrate a computer object between domains in the same forest, use the following
steps:
1. Open the ADMT MMC snap-in.
2. Right-click on the Active Directory Migration Tool folder and select the Computer
Migration Wizard.
3. On the Welcome screen, click Next.
4. On the Domain Selection page, enter the DNS or NetBIOS name of the source and
target domains. Click Next.
5. On the Computer Selection Option screen, select the option to select computer
from the domain and then click Next.
6. On the Computer Selection screen, click Add and use the object picker to select a
computer object. Click OK to return to the Computer Selection screen and then
click Next.
7. On the Organizational Unit Selection screen, enter the destination OU in the new
domain and then click Next.
8. On the Translate Objects screen, specify which objects should have new ACLs ap‐
plied in the new domain. Select any, none, or all of the following, and then click
Next to continue:
• Files and folders
• Local groups
• Printers
• Registry
• Shares
• User profiles
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• User rights
9. On the Computer Options screen, click Next to maintain the default reboot time
of 5 minutes.
10. On the Object Property Exclusion screen, select any object properties that you do
not want to migrate and then click Next.
11. On the Conflict Management screen, click Next to accept the default that will not
migrate the computer if there is a conflict.
12. On the Completing the Computer Migration Wizard screen, review the migration
settings and then click Finish to complete the move.
Using PowerShell
In the following example, the cn=jsmith object in the amer.adatum.com domain will
be moved to the emea.adatum.com domain:
Move-ADObject -Identity "cn=jsmith,cn=users,dc=amer,dc=adatum,dc=com"↵
-TargetPath "ou=MigratedUsers,dc=emea,dc=adatum,dc=com"↵
-TargetServer dc-emea1.emea.adatum.com -Credential "emea\Administrator"
Discussion
At the time of this writing, the current version of ADMT, version 3.2, is not supported
on Windows Server 2012. Therefore, you should install it on a previous version of
Windows Server as part of the migration to Windows Server 2012. You can move objects
between domains assuming you follow a few guidelines:
• The user performing the move operation must have permission to modify objects
in the parent container of both domains.
• You need to explicitly specify the target DC (serverless binds usually do not work).
This is necessary because the “Cross Domain Move” LDAP control is being used
behind the scenes. For more information on controls, see Recipe 4.4.
• The move operation must be performed against the RID master for both domains.
• When you move a user object to a different domain, its objectSID is replaced with
a new SID (based on the new domain), and the old SID is optionally added to the
sIDHistory attribute.
See Also
Recipe 4.4 for more information on LDAP controls; MS KB 238394 (How to Use the
MoveTree Utility to Move Objects Between Domains in a Single Forest); MSDN: IADs‐
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Container::MoveHere; “ADMT Guide: Migrating and Restructuring Active Directory
Domains”
4.22. Referencing an External Domain
Problem
You need to create a reference to an external Active Directory domain.
Solution
Using a graphical user interface
1. Open ADSI Edit.
2. If an entry for the naming context you want to browse is not already displayed, do
the following:
a. Right-click on ADSI Edit in the right pane and click “Connect to.”
b. Fill in the information for the naming context, container, or OU you want to
add an object to. Click on the Advanced button if you need to enter alternate
credentials.
3. Right-click on the top-level node and open a connection to the Configuration NC.
4. Right-click on the Partitions container and select New→Object. Click Next.
5. Right-click on crossRef and click Next.
6. For the cn attribute, enter the FQDN of the external domain—othercorp.com, for
example. Click Next.
7. For the nCName attribute, enter the DN of the external domain, such as dc=other
corp,dc=com. Click Next.
8. For the dnsRoot attribute, enter the DNS name of a server that can respond to LDAP
queries about the domain in question, such as dc1.othercorp.com.
9. Click Next and then Finish to create the crossRef object.
Using a command-line interface
Create an LDIF file called create_crossref.ldf with the following contents:
dn: cn=othercorp.com,cn=partitions,cn=configuration,dc=adatum,dc=com
changetype: add
objectClass: crossRef
cn: othercorp.com
nCName: dc=othercorp,dc=com
dnsRoot: dc1.othercorp.com
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Then run the following command:
> ldifde -v -i -f create_crossref.ldf
You can also create a crossRef using AdMod as follows:
> admod -config -rb cn=othercorp.com,cn=partitions↵
objectClass::crossRef cn::othercorp.com nCName::dc=othercorp,dc=com↵
dnsRoot::dc1.othercorp.com -add
Discussion
Similar to the way in which DNS servers use iterative queries to resolve hostnames that
can be resolved only by remote servers, LDAP uses referrals to resolve queries for objects
contained in naming contexts that are not hosted by the local DC. When a DC receives
any query, it will search the Partitions container for a crossRef object containing the
DN that’s being used as the Base DN of the query. If the DC locates a crossRef that
matches the search base of the query, and that crossRef indicates a naming context
that’s hosted by the domain controller itself, then the DC will perform the search locally.
If the crossRef refers to an NC that’s hosted on a remote server, the DC generates a
referral to the server that is pointed to by the crossRef object. If the DC can’t locate a
relevant crossRef object, it will use DNS to attempt to generate an additional location
to refer the client to.
In most cases, Active Directory will generate LDAP referrals automatically. However,
you should manually create a crossRef object to generate LDAP referrals for an external
domain, such as referrals to othercorp.com that are generated by the adatum.com
domain.
See Also
MS KB 241737 (How to Create a Cross-Reference to an External Domain in Active
Directory); MS KB 817872 (How to Create crossRef Objects for a DNS Namespace
Subordinate of an Existing Active Directory Forest); MSDN: Referrals [Active Direc‐
tory]; MSDN: When Referrals Are Generated [Active Directory]
4.23. Renaming an Object
Problem
You want to rename an object and keep it in its current container or OU.
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Solution
Using a graphical user interface
1. Open ADSI Edit.
2. If an entry for the naming context you want to browse is not already displayed, do
the following:
a. Right-click on ADSI Edit in the right pane and click “Connect to.”
b. Fill in the information for the naming context, container, or OU that contains
the object you want to rename. Click on the Advanced button if you need to
enter alternate credentials.
3. In the left pane, browse to the container or OU that contains the object you want
to modify. Once you’ve found the object, right-click on it and select Rename.
4. Enter the new name and click OK.
You can also rename a leaf object by using LDP as follows:
1. Open LDP.
2. From the menu, select Connection→Connect.
3. For Server, enter the name of a domain controller (or leave it blank for a serverless
bind).
4. For Port, enter 389.
5. Click OK.
6. From the menu, select Connection→Bind.
7. Accept the default and bind as the currently logged on user or select the option to
bind with credentials and then enter the credentials.
8. Click OK.
9. Click Browse→Modify RDN. For Old DN, enter the Distinguished Name of the
object that you want to rename. For New DN, enter the object’s new name.
10. Click Run to rename the object.
Using a command-line interface
To rename an object using the built-in DSMove utility, use the following syntax:
> dsmove "<ObjectDN>" -newname "<NewName>"
To use AdMod, use the following:
> admod -b "<ObjectDN>" -rename "<NewName>"
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Using PowerShell
To rename an object using PowerShell, use the following syntax:
Rename-ADObject -Identity "<Object DN>" -NewName "<New Value of 'name'
attribute>"
Discussion
Before you rename an object, you should ensure that no applications reference it by
name. You can make objects rename-safe by requiring all applications that must store
a reference to an object to use the GUID of the object, rather than the name.
The GUID (stored in the objectGUID attribute) is effectively unique and does not change
when an object is renamed.
Keep in mind that you may wish to perform other cleanup tasks when
renaming an object. In the case of a user who is changing her name,
you may wish to update her Display Name and sn attributes to match
the new CN.
Using a graphical user interface
If the parent container of the object you want to rename has a lot of objects in it, you
may want to add a new connection entry for the DN of the object you want to rename.
This may save you time searching through the list of objects in the container. You can
do this by right-clicking ADSI Edit and selecting “Connect to” under Connection Point;
select Distinguished Name and enter the DN of the object you want to rename.
You can also rename most objects within the Active Directory Users and Computers
MMC snap-in (dsa.msc) by navigating to the object in question, right-clicking on it, and
selecting Rename.
Using a command-line interface
The two parameters that are needed to rename an object are the original DN of the
object and the new RDN (-newname). The -s option can also be used to specify a server
name to work against.
See Also
MSDN: IADsContainer::MoveHere
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4.24. Deleting an Object
Problem
You want to delete an individual object.
Solution
Using a graphical user interface
1. Open ADSI Edit.
2. If an entry for the naming context you want to browse is not already displayed, do
the following:
a. Right-click on ADSI Edit in the right pane and click “Connect to.”
b. Fill in the information for the naming context, container, or OU that contains
the object you want to delete. Click on the Advanced button if you need to enter
alternate credentials.
3. In the left pane, browse to the object you want to delete.
4. Right-click on the object and select Delete.
5. Click Yes to confirm.
You can also delete an object using LDP, as follows:
1. Open LDP.
2. From the menu, select Connection→Connect.
3. For Server, enter the name of a domain controller (or leave it blank for a serverless
bind).
4. For Port, enter 389.
5. Click OK.
6. From the menu, select Connection→Bind.
7. Accept the default and bind as the currently logged on user or select the option to
bind with credentials and then enter the credentials.
8. Click OK.
9. Click Browse→Delete. For DN, enter the Distinguished Name of the object that you
want to delete.
10. Click Run to delete the object.
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Using a command-line interface
You can delete an object using the built-in dsrm utility, as well as AdMod. For dsrm, use
the following syntax:
> dsrm "<ObjectDN>"
For AdMod, enter the following:
> admod -b "<ObjectDN>" -del
Using PowerShell
To delete the “Branches” OU in the adatum.com domain, use the following command:
Remove-ADObject -Identity "ou=Branches,dc=adatum,dc=com" -Confirm:$false
Discussion
This recipe covers deleting individual objects. If you want to delete a container or OU
and all the objects in it, take a look at Recipe 4.25.
Using a graphical user interface
If the parent container of the object you want to delete has a lot of objects in it, you may
want to add a new connection entry for the DN of the object you want to delete. This
can save you time searching through the list of objects in the container and could help
avoid accidental deletions. You can do this by right-clicking ADSI Edit and selecting
“Connect to.” Under Connection Point, select Distinguished Name and enter the DN of
the object you want to delete.
You can also delete most objects within the Active Directory Users and Computers
MMC snap-in (dsa.msc) by navigating to the object in question, right-clicking on it, and
selecting Delete.
Using a command-line interface
The dsrm utility can be used to delete any type of object (there are no limitations based
on object type, as with dsadd and dsmod). The only required parameter is the DN of the
object to delete. You can also specify -noprompt to keep it from asking for confirmation
before deleting. The -s parameter can be used as well to designate a specific server to
target. AdMod will not prompt you in this manner.
See Also
Recipe 4.25 for deleting a container; MS KB 258310 (Viewing Deleted Objects in Active
Directory); MSDN: IADsContainer::Delete; MSDN: IADsDeleteOps:: DeleteObject
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4.25. Deleting a Container That Has Child Objects
Problem
You want to delete a container or organizational unit and all child objects contained
within.
Solution
Using a graphical user interface
Open ADSI Edit and follow the same steps as in Recipe 4.24. The only difference is that
you’ll be prompted to confirm twice instead of once before the deletion occurs.
Using a command-line interface
You can delete a container and its child objects using the built-in dsrm utility, as well as
AdMod. For dsrm, use the following syntax:
> dsrm "<ObjectDN>" -subtree
For AdMod, enter the following:
> admod -b "<ObjectDN>" -del -treedelete
Using PowerShell
The “Branches” OU in the adatum.com domain contains child objects. To delete it
without a confirmation prompt, use the following command:
Remove-ADObject -Identity "ou=Branches,dc=adatum,dc=com" -Recursive↵
-Confirm:$false
Discussion
As you can see from the solutions, there is not much difference between deleting a leaf
node and deleting a container that has child objects. However, there is a distinction in
what is happening in the background.
Deleting an object that has no children can be done with a simple LDAP delete operation.
On the other hand, to delete a container and its children, the tree-delete LDAP control
has to be used. If you were to do the deletion from an LDAP-based tool like LDP (the
Active Directory Administration Tool), you would first need to enable the Subtree De‐
lete control, which has an OID of 1.2.840.113556.1.4.805. LDP provides another option
to do a Recursive Delete from the client side. That will essentially iterate through all the
objects in the container, deleting them one by one. The Subtree Delete is much more
efficient, especially when dealing with large containers.
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As with the other operations we’ve discussed in this chapter (create, rename, move, and
so on), the user performing the delete operation needs to have the necessary permissions
to delete the object or objects in question. Active Directory permissions are discussed
more extensively in Chapter 14.
See Also
Recipe 4.24 for information about deleting objects; Recipe 8.19; Recipe 6.39; MSDN:
IADsDeleteOps::DeleteObject
4.26. Viewing the Created and Last-Modified Timestamp
of an Object
Problem
You want to determine when an object was either created or last updated.
Solution
Using a graphical user interface
1. Follow the steps in Recipe 4.2.
2. Ensure that createTimestamp and modifyTimestamp are included in the list of at‐
tributes to be returned by looking at Attributes under Options→Search.
Using a command-line interface
You can view the created and modified timestamps using the built-in DSQuery utility,
as well as AdFind. For DSQuery, use the following syntax:
> dsquery * "<ObjectDN>" -attr name createTimestamp modifyTimestamp
For AdFind, use the following:
> adfind -default -rb cn=Users -f "cn=Joe Smith"↵
createTimestamp modifyTimestamp
Using PowerShell
The following command gets the creation date and the last-modified date for a user
object:
Get-ADUser <sAMAccountName> -Properties * | Select Name,whenCreated,Modified
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Discussion
When an object is created or modified in Active Directory, the createTimestamp and
modifyTimestamp attributes get set with the current time. The createTimestamp at‐
tribute is replicated between domain controllers, so assuming the latest modification of
the object in question has replicated to all domain controllers, they will all contain the
timestamp when the object was created. whenChanged and modifyTimestamp are not
replicated, which means that their values will be local to an individual domain controller.
Additionally, modifyTimestamp is a constructed attribute.
See Also
Recipe 4.2 for viewing the attributes of an object; Chapter 12 for a more detailed de‐
scription of the Active Directory replication process
4.27. Modifying the Default LDAP Query Policy
Problem
You want to view or modify the default LDAP query policy of a forest. The query policy
contains settings that restrict search behavior, such as the maximum number of entries
that can be returned from a search.
Solution
Using a graphical user interface
1. Open ADSI Edit.
2. In the Configuration partition, browse to Services→Windows NT→Directory
Service→Query Policies.
3. In the left pane, click on the Query Policies container, then right-click on the
Default Query Policy object in the right pane and select Properties.
4. Double-click on the lDAPAdminLimits attribute.
5. Click on the attribute you want to modify and click Remove.
6. Modify the value in the “Value to add” box and click Add.
7. Click OK twice.
Using a command-line interface
To view the current settings, use the following command:
> ntdsutil "ldap pol" conn "con to server <DomainControllerName>" q "show values"
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To change the MaxPageSize value to 2,000, you can do the following:
> ntdsutil "ldap pol" conn "con to server <DomainControllerName>" q
ldap policy: set MaxPageSize to 2000
ldap policy: Commit Changes
Discussion
The LDAP query policy contains several settings that control how domain controllers
handle searches. By default, one query policy is defined for all domain controllers in a
forest, but you can create additional ones and apply them to a specific domain controller
or even at the site level (so that all domain controllers in the site use that policy).
Query policies are stored in the Configuration NC as queryPolicy objects. The default
query policy is located at cn=Default Query Policy,cn=Query-Policies,cn=Direc
tory Service,cn=Windows NT,cn=Services, <ConfigurationPartitionDN>. The at‐
tribute lDAPAdminLimits of a queryPolicy object is multivalued and contains each
setting for the policy in name/value pairs. Table 4-4 contains the available settings.
Table 4-4. LDAP query policy settings
Name Default value Description
MaxPoolThreads 4 per proc Maximum number of threads that are created by the DC for query execution.
MaxDatagramRecv 4096 Maximum number of datagrams that can be simultaneously processed by the
DC.
MaxReceiveBuffer 10485760 Maximum size in bytes for an LDAP request that the server will attempt to
process. If the server receives a request that is larger than this value, it will close
the connection.
InitRecvTimeout 120 secs Initial receive timeout.
MaxConnections 5000 Maximum number of open connections.
MaxConnIdleTime 900 secs Maximum amount of time a connection can be idle.
MaxPageSize 1000 Maximum number of records that will be returned by LDAP responses.
MaxQueryDuration 120 secs Maximum length of time the domain controller can execute a query.
MaxTempTableSiz 10000 Maximum size of temporary storage that is allocated to execute queries.
MaxResultSetSize 262144 Controls the total amount of data that the domain controller stores for this kind
of search. When this limit is reached, the domain controller discards the oldest
of these intermediate results to make room to store new intermediate results.
MaxNotificationPer
Conn
5 Maximum number of notifications that a client can request for a given
connection.
Instead of modifying the default LDAP query policy, you can create a new one from
scratch. In the Query Policies container (where the default query policy object is
located), create a new queryPolicy object and set the lDAPAdminLimits attribute as just
described based on the settings you want configured. Then modify the attribute query
PolicyObject on the nTDSDSA object of a domain controller you want to apply the new
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policy to. This can be done via the Active Directory Sites and Services snap-in by
browsing to the nTDSDSA object of a domain controller (cn=NTDS Settings),
right-clicking on it, and selecting Properties. You can then select the new policy from a
drop-down menu beside Query Policy. Click OK to apply the new policy.
You should not change the default query policy in production unless
you’ve done plenty of testing. Changing some of the settings may result
in unexpected application or domain controller behavior, such as a sig‐
nificant failure of your Active Directory domain controllers.
See Also
Recipe 4.19; MS KB 315071 (How to View and Set LDAP Policy in Active Directory by
Using Ntdsutil.exe)
4.28. Exporting Objects to an LDIF File
Problem
You want to export objects to an LDIF file.
Solution
Using a graphical user interface
None of the standard Microsoft tools support exporting LDIF from a GUI.
Using a command-line interface
> ldifde -f output.ldf -l <AttrList> -p <Scope> -r "<Filter>" -d "<BaseDN>"
Discussion
The LDIF specification defined in RFC 2849 describes a well-defined file-based format
for representing directory entries. The format is intended to be both human- and
machine-parseable, which adds to its usefulness. LDIF is the de facto standard for im‐
porting and exporting a large number of objects in a directory and is supported by
virtually every directory vendor, including Microsoft.
Using a command-line interface
The -f switch specifies the name of the file to use to save the entries to, -s is the DC to
query, -l is the comma-separated list of attributes to include, -p is the search scope, -r
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is the search filter, and -d is the base DN. If you encounter any problems using
ldifde, the -v switch enables verbose mode and can help identify problems.
See Also
Recipe 4.29 for importing objects using LDIF; RFC 2849 (The LDAP Data Interchange
Format [LDIF]—Technical Specification); MS KB 237677 (Using LDIFDE to Import
and Export Directory Objects to Active Directory)
4.29. Importing Objects Using an LDIF File
Problem
You want to import objects into Active Directory using an LDIF file. The file could
contain object additions, modifications, and deletions.
Solution
Using a command-line interface
To import objects using the ldifde utility, you must first create an LDIF file with the
objects to add, modify, or delete. Here is an example LDIF file that adds a user:
dn: cn=jsmith,cn=users,dc=adatum,dc=com
changetype: add
objectClass: user
samaccountname: jsmith
sn: JSmith
Once you’ve created the LDIF file, you just need to run the ldifde command to import
the new objects:
> ldifde -i -f input.ldf
Discussion
For more information on the LDIF format, check RFC 2849.
Using a command-line interface
To import with ldifde, simply specify the -i switch to turn on import mode and -f
<filename> for the file. It can also be beneficial to use the -v switch to turn on verbose
mode to get more information in case of errors. The Windows Server 2003 version of
ldifde also includes the –j switch that will create a logfile for troubleshooting purposes.
The LDIF file can specify a deletion or a modification instead of an addition. To modify
a user, set the changetype to modify. To delete a user, set the changetype to delete.
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See Also
Recipe 4.28 for information on LDIF; RFC 2849 (The LDAP Data Interchange Format
[LDIF]—Technical Specification); MS KB 237677 (Using LDIFDE to Import and Export
Directory Objects to Active Directory)
4.30. Exporting Objects to a CSV File
Problem
You want to export objects to a comma-separated values (CSV) file. The CSV file can
then be opened and manipulated from a spreadsheet application or with a text editor.
Solution
Using a graphical user interface
You can export objects to a CSV file using Active Directory Users and Computers, as
follows:
1. Open Active Directory Users and Computers.
2. Browse to the desired container or OU.
3. Right-click on the container or OU and click Export List.
4. Choose the CSV file type, name the file, and then click Save to save the file.
Using a command-line interface
You can export objects to a CSV file using the built-in csvde utility, as well as AdFind.
For csvde, use the following syntax:
> csvde -f output.csv -l <AttrList> -p <Scope> -r "<Filter>" -d "<BaseDN>"
You can also export information to a CSV file using adfind:
> adfind -b <SearchBase> -f <Filter> -csv <Attr1> <Attr2> <Attr3>
Using PowerShell
You can also export objects to a CSV file by using PowerShell. In the following command,
all user objects in the Users OU in the adatum.com domain will be exported to c:\temp
\users.csv:
Get-ADUser -SearchBase "cn=users,dc=adatum,dc=com" -Filter * |↵
Select Name,UserPrincipalName,samAccountName |↵
Export-Csv c:\temp\users.csv
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Discussion
Once you have a CSV file containing entries, you can use a spreadsheet application such
as Excel to view, sort, and manipulate the data.
Using a graphical user interface
Before performing the export, add any needed columns to the view in Active Directory
Users and Computers. To add columns, click on View and then click Add/Remove
Columns.
Using a command-line interface
The parameters used by csvde are nearly identical to those used by ldifde. The -f switch
specifies the name of the file to use to save the entries to, -s is the DC to query, -l is the
comma-separated list of attributes to include, -p is the search scope (base, onelevel,
or subtree), -r is the search filter, and -d is the base DN. If you encounter any issues,
the -v switch enables verbose mode and can help identify problems.
AdFind offers a number of additional switches to customize the behavior of CSV file
output, including the following:
-csv xxx
CSV output. xxx is an optional string that specifies the value to use for empty
attributes.
-csvdelim x
Delimiter to use for separating attributes in CSV output. The default is (,).
-csvmvdelim x
Delimiter to use for separating multiple values in output. The default is (;).
-csvq x
Character to use for quoting attributes. The default is (").
See Also
Recipe 4.31 for importing objects using a CSV file
4.31. Importing Objects Using PowerShell and a CSV File
Problem
You want to import objects into Active Directory using a CSV file.
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Solution
Using PowerShell
You must first create a CSV file containing the objects to add. The first line of the file
should contain a comma-separated list of attributes you want to set, with DN being the
first attribute. Here is an example:
DN,objectClass,cn,sn,userAccountControl,sAMAccountName,userPrincipalName
The rest of the lines should contain entries to add. If you want to leave one of the
attributes unset, then leave the value blank (followed by a comma). Here is a sample
CSV file that would add two user objects:
DN,objectClass,sn,userAccountControl,sAMAccountName,userPrincipalName
"cn=jim,cn=users,dc=adatum,dc=com",user,Smith,512,jim,jim@adatum.com
"cn=john,cn=users,dc=adatum,dc=com",user,,512,john,john@adatum.com
Once you’ve created the CSV file, you just need to import the new objects by using
PowerShell:
> -Import-CSV c:\temp\input.csv | New-ADUser
Discussion
Prior to the New-ADUser cmdlet, CSVDE was often used to import objects from a CSV
file. However, starting with Windows Server 2008, it became much more difficult to use
CSVDE due to the inability to meet password complexity requirements of a domain. CSVDE
creates users with a blank password, which usually doesn’t meet password complexity
requirements of a domain. With the New-ADUser cmdlet, new disabled users can be
created without a password, even if there is a password complexity requirement.
See Also
Recipe 4.30 for exporting objects in CSV format; Recipe 6.2; Recipe 6.3
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CHAPTER 5
Organizational Units
5.0. Introduction
An LDAP directory such as Active Directory stores data in a hierarchy of containers
and leaf nodes called the directory information tree (DIT). Leaf nodes are end points in
the tree, while containers can store other containers and leaf nodes. In Active Directory,
the two most common types of containers are organizational units (OUs) and container
objects. The container objects are generic containers that do not have any special prop‐
erties about them other than the fact that they can contain objects. Organizational
units, on the other hand, have some special properties, such as the ability to link a Group
Policy Object (GPO) to an OU. In most cases when designing a hierarchy of objects in
Active Directory, especially users and computers, you should use OUs instead of con‐
tainers. There is nothing you can do with a container that you can’t do with an OU, but
the reverse is certainly not the case.
The Anatomy of an Organizational Unit
Organizational units can be created as a child of a domain object or another OU; by
default, OUs cannot be added as a child of a container object. (See Recipe 5.13 for more
on how to work around this.) OUs themselves are represented in Active Directory by
organizationalUnit objects. Table 5-1 contains a list of some interesting attributes that
are available on organizationalUnit objects.
Table 5-1. Attributes of organizationalUnit objects
Attribute Description
description Text description of the OU.
gPLink List of GPOs that have been linked to the OU.
gPOptions Contains 1 if GPO inheritance is blocked and 0 otherwise.
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Attribute Description
msDS-Approx-Immed-Subordinates Approximate number of direct child objects in the OU. See
Recipe 5.11 for more information.
managedBy DN of user or group that is in charge of managing the OU.
ou Relative distinguished name of the OU.
modifyTimestamp Timestamp of when the OU was last modified.
createTimeStamp Timestamp of when the OU was created.
5.1. Creating an OU
Problem
You want to create an OU.
Solution
Using a graphical user interface
1. Open the Active Directory Administrative Center.
2. In the left pane, click to highlight the domain.
3. In the right pane, click New and then click Organizational Unit.
4. Enter a name for the OU, enter a description, fill in any of the desired fields, and
then click OK to create the OU.
Using a command-line interface
You can create a new OU using the built-in DSAdd utility, as well as AdMod. To create
an OU using DSAdd, use the following syntax:
> dsadd ou "<OrgUnitDN>" -desc "<Description>"
To create an OU with AdMod, use the following syntax:
> admod -b "<OrgUnitDN>" objectclass::organizationalUnit↵
description::"<Description>" -add
For example, creating the Finance OU with the description of “Finance OU” in the
adatum.com domain would look like this:
> admod -b ou=Finance,dc=adatum,dc=com objectclass::organizationalUnit↵
description::"Finance OU" -add
> AdMod V01.18.00cpp Joe Richards (joe@joeware.net) March 2012
>
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> DN Count: 1
> Using server: dc1.adatum.com
> Adding specified objects...
> DN: ou=Finance,dc=adatum,dc=com...
>
> The command completed successfully
Using PowerShell
To create an organizational unit named “Finance,” create a description of “Finance OU,”
and not protect the OU from accidental deletion, use the following command:
New-ADOrganizationalUnit "Finance" -ProtectedFromAccidentalDeletion $False↵
-Description "Finance OU"
Discussion
OUs are used to structure data within Active Directory. Typically, there are three reasons
you might need to create an OU:
Segregate objects
It is common practice to group related data into an OU. For example, user objects
and computer objects are typically stored in separate containers (in fact, this is the
default configuration with Active Directory). One reason for this is to make search‐
ing the directory easier.
Delegate administration
One of two primary reasons for creating an OU is to delegate administration. With
OUs you can give a person or group of people rights to perform certain adminis‐
trative functions on objects within an OU.
Apply a GPO
An OU is the lowest-level container object that a GPO can be applied to. If you have
different types of users within your organization that need to apply different GPOs,
the easiest way to set that up is to store the users in different OUs and apply GPOs
accordingly.
In each solution in this recipe, the description attribute of the new OU was set. This
is not a mandatory attribute, but it is good practice to set it so that others browsing the
directory have a general understanding of the purpose of the OU. Also, consider setting
the managedBy attribute to reference a user or group that is the owner of the OU. The
–ProtectedFromAccidentalDeletion parameter configures the OU so that it cannot
be deleted by using the traditional deletion methods (e.g., right-clicking on it and then
selecting Delete from the menu).
See Also
“Create an Organizational Unit Design”
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5.2. Enumerating the OUs in a Domain
Problem
You want to enumerate all containers and OUs in a domain, which effectively displays
the structure of the domain.
Solution
Using a graphical user interface
1. Open the Active Directory Users and Computers snap-in (dsa.msc).
2. If you need to change domains, right-click on Active Directory Users and Com‐
puters in the left pane, select Change Domain, enter the domain name, and click
OK.
3. In the left pane, you can browse the directory structure.
Using a command-line interface
The following command will enumerate all OUs in the current domain of the user
running the command using the built-in DSQuery utility:
> dsquery ou
You can also retrieve this information with AdFind, using the following syntax:
> adfind -default -f "objectcategory=organizationalUnit" -dn
This adfind syntax can be shortened as follows:
> adfind -default -sc oudmp
Output from the adfind command will resemble the following:
> adfind -default -f "objectcategory=organizationalUnit" -dn
>
> AdFind V01.46.00cpp Joe Richards (joe@joeware.net) March 2012
>
> Using server: dc1.adatum.com:389
> Directory: Windows Server 8
> Base DN: dc=adatum,dc=com
>
> dn:ou=Domain Controllers,dc=adatum,dc=com
> dn:ou=Finance,dc=adatum,dc=com
> dn:ou=FinanceTemps,ou=Finance,dc=adatum,dc=com
>
> 3 Objects returned
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Using PowerShell
To enumerate all OUs in the current domain using PowerShell, run the following
command:
Get-ADOrganizationalUnit -Filter * | Select DistinguishedName
Discussion
Using a graphical user interface
If you want to expand all containers and OUs within an OU, you have to manually
expand each one within ADUC or the Active Directory Administrative Center; there is
no “expand all” option.
Using a command-line interface
To enumerate both OUs and containers, you have to use a more generic dsquery com‐
mand. The following command will display all containers and OUs in the domain of
the user running the command:
> dsquery * domainroot -filter↵
"(|(objectcategory=container)(objectcategory=organizationalunit))"↵
-limit 0
5.3. Finding an OU
Problem
You want to find a specific OU within an Active Directory domain.
Solution
Using a graphical user interface
1. Open the ADUC snap-in (dsa.msc).
2. If you need to change domains, right-click on the Active Directory Users and
Computers label in the left pane, select Change Domain, enter the domain name,
and click OK.
3. Right-click on the domain node and select Find.
4. In the Find drop-down box, select Organizational Units. In the Name: text box,
enter the name of the OU.
5. Click Find Now.
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Using a command-line interface
> adfind -f "ou=<OU Name>"
Using PowerShell
To find any OU with “Test” in the name under the EMEA OU, run the following
command:
Get-ADOrganizationalUnit -SearchBase "ou=emea,dc=adatum,dc=com"↵
-LDAPFilter {(ObjectCategory=OrganizationalUnit)} |↵
Where {$_.Name -Match "Test"}
The command can be shortened to omit the search base, which will then search the
current domain, as shown in the following command:
Get-ADOrganizationalUnit -LDAPFilter {(ObjectCategory=OrganizationalUnit)} |↵
Where {$_.Name -Match "Test"}
Discussion
In a heavily nested environment, you may need to locate an OU based on its name when
you don’t necessarily know its location. By using the ADUC GUI or a command-line
tool with a search scope of subtree, you can easily recurse through the entire domain
structure to find an OU based on its name, description, or any other attribute. In AdFind,
you can use wildcards.
When designing your Active Directory structure, you should try to keep
OU nesting from becoming too deep, since processing many levels of
Group Policy Objects can greatly increase the logon times for your cli‐
ents. In the interests of keeping things simple, it’s often a good idea to
keep your OU structure shallow whenever possible.
See Also
Recipe 5.2; Recipe 5.4
5.4. Enumerating the Objects in an OU
Problem
You want to enumerate all the objects in an OU.
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