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Dead man's switch	pedal switches must simply held order machine function system often found amusement rides operator likely remain standing position lengthy period time ride motion method shortcomings.waterfall train disaster south sydney australia appeared driver slumped seat keeping pedal depressed died suddenly heart attack.also happened canadian national railway railliner passenger train problem noticed crew members train safely halted.there solutions issue used modern pedal systems.pedal vigilance function built drivers must release repress pedal response audible signal.prevents defeated circumstances standard feature british dsd systems.some types locomotive fitted threeposition pedal must normally kept mid position.
Dead man's switch	lessens likelihood accidentally defeating although may still possible deliberately so.adding vigilance function type pedal results safe system.however isolation devices still provided case equipment failure deliberate override still possible.isolation devices usually tamperevident seals fitted reason.seat switches dead mans switch also located beneath seat vehicle machine engages operator seat holding switch down.
Dead man's switch	modern tractors switch cut engine transmission engaged power takeoff spinning.riding lawn mowers switch often extreme switch cut engine even mower parked blades arent spinning.seat switches also used keep small children even starting vehicle since wouldnt weigh enough completely hold switch adjusted adolescents adults weight.key switches recreational vehicles boats personal watercraft snowmobiles control panel many amusement rides user operator cord lanyard attached wrist life jacket turn attached key mounted dead mans switch.rider fall vehicle operator least move away controls cord pulled dead mans switch turning engine setting throttle position idle.
Dead man's switch	powered boats particular cord often called kill cord powered boats use around wrist recommended may slip without cutting engine.helmsman goes overboard forced away controls engine cuts out.prevents boat continuing power control risking injury anyone water including passengers may fallen may still boat collision damage property path control boat turn prevents limits damage boat striking objects.common dangerous practice defeat kill cord fixing part boat instead operator convenience.cause accidents fatal caused limb loss.some luggage carts airports exercise treadmills feature.
Dead man's switch	case treadmills dead mans switch usually consists external magnet attached cord clips user.user falls walks away without turning treadmill switch cuts power treadmill belt.altimeter switches strategic air command developed dead mans switch nuclear bombers known special weapons emergency separation system swess ensured nuclear payload detonated event crew becoming incapacitated enemy action.purpose device unlike examples mentioned faildeadly rather failsafe.armed system would detonate onboard nuclear weapons aircraft dropped predetermined level typically due shot down.
Dead man's switch	vigilance control main safety failing basic dead mans system possibility operating device held permanently position either deliberately accidentally.vigilance control developed detect condition requiring dead mans device released momentarily reapplied timed intervals.also proposal introduce similar system automotive cruise controls.hybrid dead mans switch vigilance control device deadmans vigilance device.software software versions dead mans switches generally used people technical expertise serve several purposes sending notification friends deleting encrypting data.
Dead man's switch	nonevent triggering almost anything failing log consecutive days responding automated email ping gpsenabled telephone moving period time merely failing type code within minutes computers boot.example softwarebased dead mans switch one starts computer boots encrypt delete userspecified data unauthorized user ever gain access protected computer.googles inactive account manager allows account holder nominate someone else access services used extended period default three months.example softwarebased dead mans switch deadswitch.eu.newer solutions available public utilize growing market mobile devices instead sending automated email send push notification directly mobile device alert family friends much convenient way.
Dead man's switch	spacecraft many spacecraft use form dead mans switch guard command system failures.timer established normally reset receipt valid command including one whose sole function reset timer.timer expires spacecraft enters command loss algorithm cycles predefined sequence hardware software modes selection backup command receiver valid command received.spacecraft may also enter safe mode protect waiting commands.while similarities dead mans switch type device command loss timer actually dead mans switch aims recover hardware failure rather absence human operators.generally called watchdog timer also used extensively nuclear power control systems.
Dead man's switch	system components spacecraft put safe mode cause execute default behaviors command received within predefined time window considered dead mans switch hardware software attempts receive command human operators alternate channel autorecovering adaptive communications system dead mans switch.voyager recovered command receiver failure command loss timer.train trains basic level protection provided dead mans handle pedal.driver taken ill releases power shut emergency brake application initiated stop train.more recent safety standards consider adequate driver may slump dead mans handle continue hold even though capable controlling train.modern trains overcome risk addition vigilance system dead mans system.
Dead man's switch	buzzer bell sounds every minute order alert motorman engineer.respond moving controller releasing reapplying dead mans handle system automatically initiate emergency brake application.major rail systems world use equipment freight passenger operations.also used r new york city subway cars cbtc operation.us older locomotives produced carry feature given modular nature system uncommon find retrofitted.
Dead man's switch	aircraft airplanes use vigilance control minimize hypoxia descending lower altitude pilot unresponsive.in garmin g became first general aviation avionics suite capable automatically diverting aircraft nearest airport landing event pilot fails interact aircrafts controls respond system prompts.automation capability made possible advancements computing control navigation technologies particular importance general aviation setting since private aircraft often flown single pilot.blackmail term dead mans switch sometimes used describe form defensive blackmail insurance file release damaging material threatened anything happens person.alternative names replacement switch control name denoting specific type switch e.g.button trigger throttle pedal handle grip brakereplacement dead mans deadman enabling liveman commonly used robotics industrydrivers safety device dsd official term uk switches type used railway trainsoperator presence control opcvigilance controlalerter system higherorder systems switch activates sound alarm rather deactivates disable higherorder systemkill cord boat.
VHD (file format)	see also security switchtrain protection system references external links deadmans french trams guided trolley buses pdfkill cords lessons milly rib reportmay contain found physical hdd disk partitions file system turn contain files folders.typically used hard disk virtual machine built modern versions windows native file format microsofts hypervisor virtual machine system hyperv.the format created connectix virtual pc product known microsoft virtual pc since microsoft acquired connectix .vhdx introduced windows windows server add features flexibility missing vhd become apparent time.since june microsoft made vhd vhdx image format specifications available third parties microsoft open specification promise.features virtual hard disk allows multiple operating systems reside single host machine.
VHD (file format)	method enables developers test software different operating systems without cost hassle installing second hard disk partitioning single hard disk multiple volumes.ability directly modify virtual machines hard disk host server supports many applications includingmoving files vhd host file systembackup recoveryantivirus securityimage management patchingdisk conversion physical virtual vice versalifecycle management provisioning revhdx added hyperv windows server add larger storage capacity data corruption protection optimizations prevent performance degradation largesector physical disks.supported formats vhds implemented files reside native host file system.following types vhd formats supported microsoft virtual pc virtual serverfixed hard disk image file allocated size virtual disk.fixed vhds consist raw disk image followed vhd footer formerly bytes.dynamic hard disk image file given time large actual data written plus size header footer.
VHD (file format)	dynamic differencing vhds begin copy vhd footer padded bytes dynamic differencing vhds created microsoft products results vhdcookie string conectix beginning vhd file.differencing hard disk image set modified blocks maintained separate file referred child image comparison parent image.differencing hard disk image format allows concept undo changes enabled changes hard drive contained within vhd parent image stored separate file child image.options available undo changes vhd merge permanently vhd.different child images based parent image also allow cloning vhds least globally unique identifier guid must different.linked hard disk aka passthrough file contains link physical hard drive partition physical hard drive.advantages significant benefits result ability boot physical computer virtual hard driveease deployment organizations deploy standardized prebuilt configurations single vhd.
VHD (file format)	example software engineering organizations need specific set tools particular project could simply pull appropriatelyconfigured vhd network location.backupandrestore changes contents vhd infection virus accidental deletion critical files easily undone.multiuser isolation many current operating systems support multiple users offer varying degrees protection e.g.one user os could become infected virus infects users make changes os affect users.giving user version operating system—say creating differencing vhd based base installation os—changes particular child image would effect child images.native vhd boot native vhd boot refers ability physical computer mount boot operating system contained within vhd.windows enterprise ultimate editions support ability without host operating system present.
VHD (file format)	windows server r also compatible feature.limitations vhd format builtin limitation tib gib size dynamic differencing vhds.due sector offset table allows maximum bit quantity.calculated multiplying bytes sector.the c×h×s formula vhd specification allows maximum ×× sectors.gib also limit vhds windows virtual pc.
VHD (file format)	fewer ×× sectors gib chsvalue vhd footer uses minimum h maximum h heads sectors per track.chs algorithm determines c tsh.specification discuss cases chs value vhd footer match virtual chs geometry master boot record disk image vhd.microsoft virtual server also connectix derived limitation using virtual ide drivers tib virtual raid virtual scsi drivers used.software support virtual hard disk format initially used microsoft virtual pc microsoft virtual server.
VHD (file format)	later however microsoft used vhd format hyperv hypervisorbased virtualization technology windows server .microsoft also used format complete pc backup backup software component included windows vista windows .addition windows windows server r include support creating mounting booting vhd files.the vista later drive manager gui supports subset functions diskpart command line tool.vhds known vdisk diskpart created formatted attached mounted detached unmounted merged differencing vhds compacted vhds ntfs host file system.compacting typically two step procedure first unused sectors vhd filled zeros diskpart use ntfs feature sparse files eliminate runs zeros vhd.
VHD (file format)	virtual machine additions older vpc versions virtual machine integration features windows virtual pc contain precompact iso images first step supported guest systems.thirdparty products also use vhd file format.oracle virtualbox part sun xvm line sun microsystems supports vhd versions later.red gate software windocks introduced vhd based support sql server database cloning.offline modification sometimes useful modify vhd file without booting operating system.hyperv features offline vhd manipulation providing administrators ability securely access files within vhd without instantiate virtual machine.
VHD (file format)	provides administrators granular access vhds ability perform management tasks offline.windows disk management mmc plugin directly mount vhd file drive letter windows server newer.for situations mounting vhd within operating system undesirable several programs enable software developers inspect modify vhd files including .net discutils winimage rsoft hyperv vhd explorer.zip supports extraction inspection vhd files.virtual floppy disk vfd virtual floppy disk vfd related file format used microsoft virtual pc microsoft automated deployment services microsoft virtual server .vfd contains image kb lowdensity .
VHD (file format)	mb highdensity .mb dmf .inch floppy disk mounted virtual pc.virtual machine software vmware workstation vmware player mount raw floppy images way.windows virtual pc windows version .offer user interface manipulating virtual floppy disks however still supports physical virtual floppy disks via scripting.hyperv vfd files usable vm settings generation virtual machines.
VHD (file format)	generation virtual machines emulate floppy controller support floppy disk images.virtual hard disk vhdx vhdx virtual hard disk v successor format vhd.vhd capacity limit gb vhdx capacity limit tb.disk images newer format filename extension vhdx used instead vhd.vhdx protects power failures used hyperv.
Google Photos	vhdx mounted like vhd.see also vmdkqcowvirtual disk imageapple disk imagevhd set referencesannounced may spun google companys former social network.as june free tier newly uploaded photo video counts towards gb free storage quota shared across users google services exception current pixel phones.previous free tier unlimited photos videos megapixels p resolution respectively anything larger gets downscaled sizes ended day.the service automatically analyzes photos identifying various visual features subjects.users search anything photos service returning results three major categories people places things.computer vision google photos recognizes faces humans pets well grouping similar ones together feature available certain countries due privacy laws geographic landmarks eiffel tower subject matter including birthdays buildings animals food more.different forms machine learning photos service allow recognition photo contents automatically generate albums animate similar photos quick videos surface past memories significant times improve quality photos videos.may google announced several updates google photos including reminders suggested sharing photos shared photo libraries two users physical albums.
Google Photos	photos automatically suggested collections based face location trip distinction.google photos received critical acclaim decoupling google .reviewers praised updated photos service recognition technology search apps loading times.nevertheless privacy concerns raised including googles motivation building service well relationship governments possible laws requiring google hand users entire photo history.google photos seen strong user adoption.reached million users five months million one year million two years passed billion user mark four years initial launch.
Google Photos	google reports approximately billion photos videos uploaded service every week trillion photos stored service total.history google photos standalone successor photo features previously embedded google companys social network.google launched social network compete facebook service never became popular facebook social networking photo sharing.google offered photo storage organizational tools surpassed facebooks power though google lacked user base use it.leaving social network affiliation photos service changed association sharing platform private library platform.in december google added shared albums google photos.
Google Photos	users pool photos videos album share album google photos users.recipient join add photos videos also get notifications new pics added.users also save photos videos shared albums add private collection.unlike native photos service within ios google photos permits full resolution sharing across android ios platforms two.on february google announced picasa desktop application would discontinued march followed closure picasa web albums service may .google stated primary reason retiring picasa wanted focus efforts entirely single photo service crossplatform webbased google photos.in june google updated photos include automatically generated albums.
Google Photos	event trip photos group photos together suggest creating album alongside maps show geographic travel location pins exact places.users also add text captions describe photos.october google announced multiple significant updates google photos surfaces old memories people identified users recent photos occasionally highlights subset photos user recently taken lot images specific subject makes animations videos well photos photo animations present since start displaying specific photos intermixed short excerpts longer videos videos attempts detect sideways upside photos prompts user accept reject different orientation.features google touts machine learning work user interaction required.in november google released separate app photoscan users scan printed photos service.app released ios android uses scanning process users must center camera four dots overlay printed image software combine photographs highresolution digital image fewest possible defects.
Google Photos	later month google added deep blue slider feature lets users change color saturation skies without degrading image quality inadvertently changing colors objects elements photos.in february google updated albums tab android app include three separate sections one phones camera roll different views sorting options people location another photos taken inside apps third actual photo albums.march google added automatic white balance feature service.android app website first receive feature later rollout ios app.later march updates service enabled uploading photos lightweight preview quality immediate viewing slow cellular networks higherquality upload later faster wifi.feature also extends sharing photos lowresolution image sent updated higherquality version.
Google Photos	april google added video stabilization.feature creates duplicate video avoid overwriting original clip.in may google announced several updates google photos.suggested sharing reminds users share captured photos fact also groups photos based faces suggests recipients based facial recognition.shared libraries lets two users share central repository photos specific categories images.photo books physical collections photos offered either softcover hardcover albums photos automatically suggesting collections based face location trip distinction.
Google Photos	towards end month google introduced archive feature lets users hide photos main timeline view without deleting them.archived content still appears relevant albums search.june new sharing features announced may began rolling users.in december google doubled number photos videos users store private google photos live album.number increased photos equivalent capacity shared albums.in september google photos introduced new social medialike feature called memories similar stories feature instagram facebook highlights past photos give users nostalgic feeling.on june google photos introduced major redesign mobile web apps accompanied new simplified logo.features service apps android ios operating systems website.
Google Photos	users back photos cloud service becomes accessible devices.the photos service analyzes organizes images groups identify features beaches skylines snowstorm toronto.applications search window users shown potential searches groups photos three major categories people places things.service analyzes photos similar faces groups together people category.also track faces age.places category uses geotagging data also determine locations older pictures analyzing major landmarks e.g.
Google Photos	photos containing eiffel tower.things category processes photos subject matter birthdays buildings cats concerts food graduations posters screenshots etc.users manually remove categorization errors.google lens also integrated service.recipients shared images view web galleries without needing download app.users swipe fingers across screen adjust services photo editing settings opposed using sliders.
Google Photos	images easily shared social networks google facebook twitter services.application generates web links google photos users nonusers access.a new feature showing heat map photo locations added .storage google photos three storage settings high quality storage saver original quality express quality unavailable certain locations.high quality includes photo video storage photos megapixels videos p resolution maximum resolutions average smartphone users .original quality preserves original resolution quality photos videos.
Google Photos	express quality includes photo video storage photos megapixels videos p resolution.for first three generations google pixel phones google photos offers unlimited storage original quality free.original pixel limits offer pixel offered unlimited storage original quality photos videos taken january january respectively photos videos taken dates uploaded high quality instead.pixel onwards offer unlimited storage original quality pixel pixel pixel g pixel offering month trial gb google one plan new members instead.in november google photos announced would ending offering free unlimited storage photos uploaded high quality express quality starting june due rising demand storage.june google photos changed name high quality storage saver.move part effort reduce googles reliance adbased revenue increase subscriptions.
Google Photos	existing photos remain unaffected new photos count towards users storage quota shared across google drive gmail google photos.owners first five generations google pixel smartphones remain exempt change.growth october five months launch service google announced google photos million users uploaded .petabytes photos videos.in may one year release google photos google announced service million monthly active users.statistics revealed least .
Google Photos	petabytes photosvideos uploaded trillion labels applied billion selfies .billion animations collages effects created based user content.in may google announced google photos million users upload .billion photos every day.in november google announced trillion photos stored google photos every week billion new photos videos uploaded.reception may release google photos reviewers wrote service among best kind.walt mossberg recode declared service best cloud photo storage competition amazon amazon drive apple icloud dropbox microsoft onedrive.
Google Photos	jacob kastrenakes verge wrote release made google major competitor photo storage market pricing structure obsoleted idea paying photo storage.sarah mitroff lynn la cnet wrote services phone tablet apps particularly good google photos streamlined design yahoos flickr organizing features apples icloud photo service.kastrenakes described services may release evidence google spinning best features google social network.stated photos service always excellent liked users would able use service without signing new social network.mossberg described release liberation day photos features effectively hidden widely ignored social network.services strategy described josh lowensohn verge put data googles servers accessed universally.mossberg liked services search function writing search massachusetts instantly brought loads photos subjects.
Google Photos	lowensohn noted services speed intelligence especially ability sort unorganized photos well photo loading times search speeds simple photo editing tools.kastrenakes compared services new image analysis technology unveiled flickr earlier month.mossberg thought face grouping feature remarkably accurate impressed subjectbased grouping.surprised search boats found cape cod fishing boats venetian gondolas also noted errors professional photograph registering screenshot.pc magazines john c. dvorak concerned services privacy.particularly concerned googles motivation building service companys relationships existing governments potential laws would require google provide users entire history photos upon request.
Google Photos	dvorak compared scenario inviting others scrounge underwear drawer.criticized services sync functions preferred folders images unsorted flat database.dvorak also highlighted services poor choice photos animate lack longevity guarantees considering companys abrupt cancellation google reader.ultimately suggested users instead use portable hard drive considered safer cheap.see also amazon photosapple photosflickrpicasa web albums references external links official website
Symantec Operations Readiness Tools	sort identifies risks data centers provides remediation recommendations.symantec currently charge customers sort.process sort uses data collector collect configuration environmental data veritas volume manager vxvm veritas file system vxfs vcs netbackup symantec enterprise products.data analyzed potential problems risks summarized reports.sort produces three types reports symantec enterprise productsproduct licensing inventoryinstallation upgraderisk assessmentsort performs environmentspecific checks produce reports.risk assessment report example based separate checks.product licensing inventory report product licensing inventory report lists installed software binaries license keys.
Symantec Operations Readiness Tools	installation upgrade report installation upgrade report lists environmentspecific prerequisites must met installing upgrading symantec enterprise products.example report lists required operating system patches need installed installing symantec enterprise product.risk assessment report risk assessment report provides environmentspecific configuration assessment recommendations increase performance availability utilization.for example one checks risk assessment report lists volumes whose mirrors composed logical units disk array.logical volumes mirrored higher availability mirrored across separate disk array controllers.mirroring logical volumes across separate disk array controllers allows logical volumes continue operate one disk array fail.
Dynamic Host Configuration Protocol	see also netbackupveritas cluster file systemveritas cluster serververitas file systemveritas storage foundationveritas volume managerveritas volume replicator external links symantec operations readiness toolssymantec owner veritas.referencesconnected network periodically thereafter client requests set parameters dhcp server using dhcp protocol.dhcp implemented networks ranging size residential networks large campus networks regional isp networks.many routers residential gateways dhcp server capability.residential network routers receive unique ip address within isp network.within local network dhcp server assigns local ip address device.dhcp services exist networks running internet protocol version ipv well version ipv.ipv version dhcp protocol commonly called dhcpv.
Dynamic Host Configuration Protocol	history reverse address resolution protocol rarp defined rfc configuration simple devices diskless workstations suitable ip address.acting data link layer made implementation difficult many server platforms.required server present individual network link.rarp superseded bootstrap protocol bootp defined rfc september .introduced concept relay agent allowed forwarding bootp packets across networks allowing one central bootp server serve hosts many ip subnets.dhcp based bootp dynamically allocate ip addresses pool reclaim longer use.
Dynamic Host Configuration Protocol	also used deliver wide range extra configuration parameters ip clients including platformspecific parameters.dhcp first defined rfc october due errors editorial process almost immediately reissued rfc .four years later dhcpinform message type small changes added rfc remains core standard ipv networks updates rfc rfc rfc rfc .dhcpv initially described rfc updated many subsequent rfcs.rfc added dhcpv mechanism prefix delegation stateless address autoconfiguration added rfc .overview internet protocol ip defines devices communicate within across local networks internet.dhcp server manage ip settings devices local network e.g.
Dynamic Host Configuration Protocol	assigning ip addresses devices automatically dynamically.dhcp operates based client–server model.computer device connects network dhcp client software sends dhcp broadcast query requesting necessary information.dhcp server network may service request.dhcp server manages pool ip addresses information client configuration parameters default gateway domain name name servers time servers.receiving dhcp request dhcp server may respond specific information client previously configured administrator specific address information valid entire network time period allocation lease valid.
Dynamic Host Configuration Protocol	dhcp client typically queries information immediately booting periodically thereafter expiration information.dhcp client refreshes assignment initially requests parameter values dhcp server may assign new address based assignment policies set administrators.on large networks consist multiple links single dhcp server may service entire network aided dhcp relay agents located interconnecting routers.agents relay messages dhcp clients dhcp servers located different subnets.depending implementation dhcp server may three methods allocating ip addressesdynamic allocationa network administrator reserves range ip addresses dhcp dhcp client lan configured request ip address dhcp server network initialization.requestandgrant process uses lease concept controllable time period allowing dhcp server reclaim reallocate ip addresses renewed.automatic allocationthe dhcp server permanently assigns ip address requesting client range defined administrator.like dynamic allocation dhcp server keeps table past ip address assignments preferentially assign client ip address client previously had.manual allocationthis method also variously called static dhcp allocation fixed address allocation reservation macip address binding.
Dynamic Host Configuration Protocol	administrator maps unique identifier client id mac address client ip address offered requesting client.dhcp servers may configured fall back methods fails.dhcp services used internet protocol version ipv ipv.details protocol ipv ipv differ sufficiently may considered separate protocols.ipv operation devices may alternatively use stateless address autoconfiguration.ipv hosts may also use linklocal addressing achieve operations restricted local network link.
Dynamic Host Configuration Protocol	operation dhcp employs connectionless service model using user datagram protocol udp.implemented two udp port numbers operations bootstrap protocol bootp.udp port number destination port server udp port number used client.dhcp operations fall four phases server discovery ip lease offer ip lease request ip lease acknowledgement.stages often abbreviated dora discovery offer request acknowledgement.the dhcp operation begins clients broadcasting request.client server different broadcast domains dhcp helper dhcp relay agent may used.
Dynamic Host Configuration Protocol	clients requesting renewal existing lease may communicate directly via udp unicast since client already established ip address point.additionally broadcast flag bit byte flags field bits reserved set client use indicate way broadcast unicast receive dhcpoffer x broadcast x unicast.usually dhcpoffer sent unicast.hosts cannot accept unicast packets ip addresses configured flag used work around issue.discovery dhcp client broadcasts dhcpdiscover message network subnet using destination address ... limited broadcast specific subnet broadcast address directed broadcast.
Dynamic Host Configuration Protocol	dhcp client may also request last known ip address.client remains connected network server may grant request.otherwise depends whether server set authoritative not.authoritative server denies request causing client issue new request.nonauthoritative server simply ignores request leading implementationdependent timeout client expire request ask new ip address.for example htype set specify medium used ethernet hlen set ethernet address mac address octets long.
Dynamic Host Configuration Protocol	chaddr set mac address used client.options set well.offer dhcp server receives dhcpdiscover message client ip address lease request dhcp server reserves ip address client makes lease offer sending dhcpoffer message client.message contains clients client id traditionally mac address ip address server offering subnet mask lease duration ip address dhcp server making offer.dhcp server may also take notice hardwarelevel mac address underlying transport layer according current rfcs transport layer mac address may used client id provided dhcp packet.the dhcp server determines configuration based clients hardware address specified chaddr client hardware address field.
Dynamic Host Configuration Protocol	server ... specifies clients ip address yiaddr ip address field.request response dhcp offer client replies dhcprequest message broadcast server requesting offered address.client receive dhcp offers multiple servers accept one dhcp offer.client produce gratuitous arp order find host present network ip address.reply host host ip configuration network message broadcast server showing acceptance ip address.
Dynamic Host Configuration Protocol	client must send server identification option request message indicating server whose offer client selected.section .item dhcp servers receive message withdraw offers made client return offered ip address pool available addresses.acknowledgement dhcp server receives dhcprequest message client configuration process enters final phase.acknowledgement phase involves sending dhcpack packet client.
Dynamic Host Configuration Protocol	packet includes lease duration configuration information client might requested.point ip configuration process completed.the protocol expects dhcp client configure network interface negotiated parameters.after client obtains ip address probe newly received address e.g.arp address resolution protocol prevent address conflicts caused overlapping address pools dhcp servers.probe finds another computer using address computer send dhcpdecline broadcast server.information dhcp client may request information server sent original dhcpoffer.
Dynamic Host Configuration Protocol	client may also request repeat data particular application.example browsers use dhcp inform obtain web proxy settings via wpad.releasing client sends request dhcp server release dhcp information client deactivates ip address.client devices usually know users may unplug network protocol mandate sending dhcp release.client configuration parameters dhcp server provide optional configuration parameters client.
Dynamic Host Configuration Protocol	rfc describes available dhcp options defined internet assigned numbers authority iana dhcp bootp parameters.a dhcp client select manipulate overwrite parameters provided dhcp server.unixlike systems clientlevel refinement typically takes place according values configuration file etcdhclient.conf.options options octet strings varying length.called type–length–value encoding.first octet option code second octet number following octets remaining octets code dependent.for example dhcp messagetype option offer would appear x x x x code dhcp message type x means one octet follows x value offer.the following tables list available dhcp options listed rfc iana registry.
Dynamic Host Configuration Protocol	dhcp message types table lists dhcp message types documented rfc rfc rfc rfc rfc .codes value dhcp extension shown thetable above.client vendor identification option exists identify vendor functionality dhcp client.information variablelength string characters octets meaning specified vendor dhcp client.one method dhcp client communicate server using certain type hardware firmware set value dhcp requests called vendor class identifier vci option .
Dynamic Host Configuration Protocol	method allows dhcp server differentiate two kinds client machines process requests two types modems appropriately.types settop boxes also set vci option inform dhcp server hardware type functionality device.value option set gives dhcp server hint required extra information client needs dhcp response.extensions relay agent information suboptions relay agent information option option specifies container attaching suboptions dhcp requests transmitted dhcp relay dhcp server.relaying small networks one ip subnet managed dhcp clients communicate directly dhcp servers.
Dynamic Host Configuration Protocol	however dhcp servers also provide ip addresses multiple subnets.case dhcp client yet acquired ip address cannot communicate directly dhcp server subnet clients broadcast received subnet.in order allow dhcp clients subnets directly served dhcp servers communicate dhcp servers dhcp relay agents installed subnets.dhcp client broadcasts local link relay agent receives broadcast transmits one dhcp servers using unicast.relay agent stores ip address field giaddr field dhcp packet.dhcp server uses giaddrvalue determine subnet relay agent received broadcast allocates ip address subnet.
Dynamic Host Configuration Protocol	dhcp server replies client sends reply giaddraddress using unicast.relay agent retransmits response local network.in situation communication relay agent dhcp server typically uses source destination udp port .client states described rfc section .dhcp client receive messages serverdhcpofferdhcpackdhcpnakthe client moves dhcp states depending server responds messages client sends.reliability dhcp ensures reliability several ways periodic renewal rebinding section .. failover.
Dynamic Host Configuration Protocol	dhcp clients allocated leases last period time.clients begin attempt renew leases half lease interval expired.section .. paragraph sending unicast dhcprequest message dhcp server granted original lease.server unreachable fail respond dhcprequest.however case client repeats dhcprequest time time section .. paragraph dhcp server comes back becomes reachable dhcp client succeed contacting renew lease.if dhcp server unreachable extended period time section .. paragraph dhcp client attempt rebind broadcasting dhcprequest rather unicasting it.
Dynamic Host Configuration Protocol	broadcast dhcprequest message reach available dhcp servers.dhcp server able renew lease time.in order rebinding work client successfully contacts backup dhcp server server must accurate information clients binding.maintaining accurate binding information two servers complicated problem servers able update lease database must mechanism avoid conflicts updates independent servers.proposal implementing faulttolerant dhcp servers submitted internet engineering task force never formalized.if rebinding fails lease eventually expire.lease expires client must stop using ip address granted lease.
Dynamic Host Configuration Protocol	section .. paragraph time restart dhcp process beginning broadcasting dhcpdiscover message.since lease expired accept ip address offered it.new ip address presumably different dhcp server able use network.however since ip address changed ongoing connections broken.ipv networks basic methodology dhcp developed networks based internet protocol version ipv.
Dynamic Host Configuration Protocol	since development deployment ipv networks dhcp also used assigning parameters networks despite inherent features ipv stateless address autoconfiguration.ipv version protocol designated dhcpv.security base dhcp include mechanism authentication.vulnerable variety attacks.attacks fall three main categoriesunauthorized dhcp servers providing false information clients.unauthorized clients gaining access resources.resource exhaustion attacks malicious dhcp clients.because client way validate identity dhcp server unauthorized dhcp servers commonly called rogue dhcp operated networks providing incorrect information dhcp clients.
Dynamic Host Configuration Protocol	serve either denialofservice attack preventing client gaining access network connectivity maninthemiddle attack.dhcp server provides dhcp client server ip addresses ip address one dns servers attacker convince dhcp client dns lookups dns server therefore provide answers dns queries client.turn allows attacker redirect network traffic allowing eavesdrop connections client network servers contacts simply replace network servers own.because dhcp server secure mechanism authenticating client clients gain unauthorized access ip addresses presenting credentials client identifiers belong dhcp clients.also allows dhcp clients exhaust dhcp servers store ip addresses—by presenting new credentials time asks address client consume available ip addresses particular network link preventing dhcp clients getting service.dhcp provide mechanisms mitigating problems.relay agent information option protocol extension rfc usually referred industry actual number option allows network operators attach tags dhcp messages messages arrive network operators trusted network.
Dynamic Host Configuration Protocol	tag used authorization token control clients access network resources.client access network upstream relay agent lack authentication prevent dhcp server operator relying authorization token.another extension authentication dhcp messages rfc provides mechanism authenticating dhcp messages.rfc seen widespread adoption problems managing keys large numbers dhcp clients.book dsl technologies remarked thatthere numerous security vulnerabilities identified security measures proposed rfc .fact combined introduction .x slowed deployment takerate authenticated dhcp never widely deployed.
Autodesk Vault	book notes thatthere implementations dhcp authentication.challenges key management processing delays due hash computation deemed heavy price pay perceived benefits.architectural proposals involve authenticating dhcp requests using .x pana transport eap.ietf proposal made including eap dhcp socalled eapodhcp appear progressed beyond ietf draft level last dates .ietf standards documents rfc dynamic host configuration protocolrfc dhcp options bootp vendor extensionsrfc dhcp relay agent information optionrfc dynamic host configuration protocol dhcp domain search optionrfc reclassifying dynamic host configuration protocol version four dhcpv optionsrfc information refresh time option dynamic host configuration protocol ipvrfc nodespecific client identifiers dynamic host configuration protocol version four dhcpvrfc detecting network attachment ipv dnavrfc classless static route option dynamic host configuration protocol dhcp version rfc dhcp reconfigure extensionrfc dynamic host configuration protocol dhcp leasequeryrfc dhcpv bulk leasequeryrfc active dhcpv lease query see also notes references external links media related dynamic host configuration protocol dhcp wikimedia commonshelps design teams track work progress maintain version control multiuser environments.allows organize reuse designs consolidating product information reducing need recreate designs scratch.users store search cad data autodesk inventor dwg dwf files noncad documents microsoft word microsoft excel files.overview vault environment functions client server application central sql database autodesk data management server adms applications installed windowsbased server client access granted via various clients thick client vault explorer application integrations.adms acts middleware handles client transactions sql database.
Autodesk Vault	vault explorer functions client application intended run alongside companion cad software.vault explorer ui user interface intended appearance similar microsoft outlook display vault folder structure file metadata form grid preview pane detailed information.autodesk vault file versioning system records progression edits file undergone.files associated metadata indexed sql base data management system searchable vault client interface.information files include version history uses composed list children used list parents well light weight viewable form autodesk design web format dwf file automatically published upon checkin.users intend edit file file checkedout edits made.
Autodesk Vault	user satisfied changes file checkedin new file version containing new changes available users workgroup.inprocess file changes file saves hidden users changes checkedin.files edited renamed moved folder structure vault database automatically updates file references related files.vault intended core data management strategy autodesks design products therefore addins many autodesks design solutions.adms also plays another role hosts autodesk inventors content center standard parts library use inventor desired hosted central location.autodesk vault family products autodesk vault product family stack products offering incremental functionality previous product.base autodesk vault included many autodesk design applications additional functionality available based needs organization.
Autodesk Vault	following products part autodesk vault family.vault workinprocess data managementvault workgroup customisation revision management securityvault professional professional level capabilities erp integration item master morenote release autodesk vault manufacturing renamed autodesk vault professional.also formerly known autodesk productstream prior releases.family subsequently simplified release retirement autodesk vault collaboration functionality matrix legendv vault basevw vault workgroupvp vault professional history autodesk vault initially known truevault part acquisition company called trueinnovations inc. based eagan minnesota.trueinnovations started two entrepreneurs brian roepke dean brisson .company founded basis bringing affordable tool managing engineering data market.after asset acquisition trueinnovations autodesk autodesk began integration product manufacturing product line starting autodesk inventor.
Autodesk Vault	supported applications release following applications supported autodesk vault.integrations available vault workgroup above.base vault software timeline references external links autodesk vault familyhelps design teams track work progress maintain version control multiuser environments.allows organize reuse designs consolidating product information reducing need recreate designs scratch.users store search cad data autodesk inventor dwg dwf files noncad documents microsoft word microsoft excel files.overview vault environment functions client server application central sql database autodesk data management server adms applications installed windowsbased server client access granted via various clients thick client vault explorer application integrations.adms acts middleware handles client transactions sql database.
Autodesk Vault	vault explorer functions client application intended run alongside companion cad software.vault explorer ui user interface intended appearance similar microsoft outlook display vault folder structure file metadata form grid preview pane detailed information.autodesk vault file versioning system records progression edits file undergone.files associated metadata indexed sql base data management system searchable vault client interface.information files include version history uses composed list children used list parents well light weight viewable form autodesk design web format dwf file automatically published upon checkin.users intend edit file file checkedout edits made.
Autodesk Vault	user satisfied changes file checkedin new file version containing new changes available users workgroup.inprocess file changes file saves hidden users changes checkedin.files edited renamed moved folder structure vault database automatically updates file references related files.vault intended core data management strategy autodesks design products therefore addins many autodesks design solutions.adms also plays another role hosts autodesk inventors content center standard parts library use inventor desired hosted central location.autodesk vault family products autodesk vault product family stack products offering incremental functionality previous product.base autodesk vault included many autodesk design applications additional functionality available based needs organization.
Autodesk Vault	following products part autodesk vault family.vault workinprocess data managementvault workgroup customisation revision management securityvault professional professional level capabilities erp integration item master morenote release autodesk vault manufacturing renamed autodesk vault professional.also formerly known autodesk productstream prior releases.family subsequently simplified release retirement autodesk vault collaboration functionality matrix legendv vault basevw vault workgroupvp vault professional history autodesk vault initially known truevault part acquisition company called trueinnovations inc. based eagan minnesota.trueinnovations started two entrepreneurs brian roepke dean brisson .company founded basis bringing affordable tool managing engineering data market.after asset acquisition trueinnovations autodesk autodesk began integration product manufacturing product line starting autodesk inventor.
Shearon Harris Nuclear Power Plant	supported applications release following applications supported autodesk vault.integrations available vault workgroup above.base vault software timeline references external links autodesk vault familynamed honor w. shearon harris former president carolina power light predecessor progress energy inc.. located new hill north carolina united states miles km southwest raleigh generates mwe foot natural draft cooling tower uses harris lake cooling.reactor achieved criticality january began providing power commercially may year.the shearon harris site originally designed four reactors still space available weakening demand despite growing population resulted three reactors canceled.final cost approached .b including safety upgrades mandated three mile island accident.on november operator applied nuclear regulatory commission nrc renewal extension plants operating license.the nrc granted renewal december extending license forty years sixty.units february progress filed application nuclear regulatory commission nrc combined construction operating license col. seeks build two mwe westinghouse ap pressurized water reactors.although nrc already certified ap design application review expected take months.
Shearon Harris Nuclear Power Plant	new reactors would operational .expansion plant would require raising water level harris lake feet decreasing size wake countys largest park cape fear river backup water source.on january officials nuclear regulatory commission announced electrical generator damaged unit reactor three mile island would used shearon harris.generator refurbished installed refueling outage november .on may duke submitted request nrc suspend review harris units combined license application cola effectively halting development project.duke determined forecast operating dates proposed reactors falls outside fifteenyear planning horizon utilized state regulators demonstration need evaluation.cola remains docketed however leaving door open duke restart activities.reactor data shearon harris nuclear power plant consists one operational reactor.
Shearon Harris Nuclear Power Plant	three additional units cancelled.two additional reactors planned cancelled .safety nuclear regulatory commission inspections september harris plant one three plants country nuclear regulatory commission nrc findings past quarters inspections.the nrcs risk estimate earthquake intense enough cause core damage reactor shearon harris according nrc study published august .surrounding population nuclear regulatory commission defines two emergency planning zones around nuclear power plants plume exposure pathway zone radius miles km concerned primarily exposure inhalation airborne radioactive contamination ingestion pathway zone miles km concerned primarily ingestion food liquid contaminated radioactivity.the u.s. population within miles km shearon harris increase .percent decade according analysis u.s. census data msnbc.com.
Shearon Harris Nuclear Power Plant	u.s. population within miles km increase .percent since .cities within miles include raleigh miles city center durham miles city center fayetteville miles city center.during femas recent evaluation state local governments plans preparedness included emergency operations plant deficiencies areas requiring corrective actions identified.ncwarn concerns antinuclear group n.c. waste awareness reduction network ncwarn questioned facilitys safety security record calling insufficient claiming dangerous nuclear plant us.however plants technical security systems passed nuclear regulatory commission nrc standards including protection security worker area resident injured result plants operation.
Shearon Harris Nuclear Power Plant	spent fuel pools project censored nonprofit investigative journalism project ranked safety issues shearon harris th underreported story year risk fires largest spentfuel pools country.in august nc warn dropped lawsuit progress energy intended delay prevent expansion shearon harris claiming continuing legal battle would cost least .shutdown may shearon harris unit initiated unplanned shutdown reviews ultrasonic data refueling outage spring determined flaw inside thick reactor pressure vessel head.flaw near nozzle control rod drive mechanism attributed primary water stress corrosion cracking though actual leakage detected.due high radiation levels repairs required robotic aid.references external links harris energy environmental centernrc treatise circuit integrity measures including shearon harrisnrc public information regarding units expansion proposalnuclear regulatory commission approves construction first nuclear units yearsindy news article local opposition nrc safety oversighthttp – quarterly performance summary nrchttp
Shearon Harris Nuclear Power Plant	named honor w. shearon harris former president carolina power light predecessor progress energy inc.. located new hill north carolina united states miles km southwest raleigh generates mwe foot natural draft cooling tower uses harris lake cooling.reactor achieved criticality january began providing power commercially may year.the shearon harris site originally designed four reactors still space available weakening demand despite growing population resulted three reactors canceled.final cost approached .b including safety upgrades mandated three mile island accident.on november operator applied nuclear regulatory commission nrc renewal extension plants operating license.the nrc granted renewal december extending license forty years sixty.units february progress filed application nuclear regulatory commission nrc combined construction operating license col. seeks build two mwe westinghouse ap pressurized water reactors.although nrc already certified ap design application review expected take months.
Shearon Harris Nuclear Power Plant	new reactors would operational .expansion plant would require raising water level harris lake feet decreasing size wake countys largest park cape fear river backup water source.on january officials nuclear regulatory commission announced electrical generator damaged unit reactor three mile island would used shearon harris.generator refurbished installed refueling outage november .on may duke submitted request nrc suspend review harris units combined license application cola effectively halting development project.duke determined forecast operating dates proposed reactors falls outside fifteenyear planning horizon utilized state regulators demonstration need evaluation.cola remains docketed however leaving door open duke restart activities.reactor data shearon harris nuclear power plant consists one operational reactor.
Shearon Harris Nuclear Power Plant	three additional units cancelled.two additional reactors planned cancelled .safety nuclear regulatory commission inspections september harris plant one three plants country nuclear regulatory commission nrc findings past quarters inspections.the nrcs risk estimate earthquake intense enough cause core damage reactor shearon harris according nrc study published august .surrounding population nuclear regulatory commission defines two emergency planning zones around nuclear power plants plume exposure pathway zone radius miles km concerned primarily exposure inhalation airborne radioactive contamination ingestion pathway zone miles km concerned primarily ingestion food liquid contaminated radioactivity.the u.s. population within miles km shearon harris increase .percent decade according analysis u.s. census data msnbc.com.
Shearon Harris Nuclear Power Plant	u.s. population within miles km increase .percent since .cities within miles include raleigh miles city center durham miles city center fayetteville miles city center.during femas recent evaluation state local governments plans preparedness included emergency operations plant deficiencies areas requiring corrective actions identified.ncwarn concerns antinuclear group n.c. waste awareness reduction network ncwarn questioned facilitys safety security record calling insufficient claiming dangerous nuclear plant us.however plants technical security systems passed nuclear regulatory commission nrc standards including protection security worker area resident injured result plants operation.
Shearon Harris Nuclear Power Plant	spent fuel pools project censored nonprofit investigative journalism project ranked safety issues shearon harris th underreported story year risk fires largest spentfuel pools country.in august nc warn dropped lawsuit progress energy intended delay prevent expansion shearon harris claiming continuing legal battle would cost least .shutdown may shearon harris unit initiated unplanned shutdown reviews ultrasonic data refueling outage spring determined flaw inside thick reactor pressure vessel head.flaw near nozzle control rod drive mechanism attributed primary water stress corrosion cracking though actual leakage detected.due high radiation levels repairs required robotic aid.references external links harris energy environmental centernrc treatise circuit integrity measures including shearon harrisnrc public information regarding units expansion proposalnuclear regulatory commission approves construction first nuclear units yearsindy news article local opposition nrc safety oversighthttp – quarterly performance summary nrchttp
Load balancing (computing)	load balancing optimize response time avoid unevenly overloading compute nodes compute nodes left idle.load balancing subject research field parallel computers.two main approaches exist static algorithms take account state different machines dynamic algorithms usually general efficient require exchanges information different computing units risk loss efficiency.problem overview load balancing algorithm always tries answer specific problem.among things nature tasks algorithmic complexity hardware architecture algorithms run well required error tolerance must taken account.therefore compromise must found best meet applicationspecific requirements.
Load balancing (computing)	nature tasks efficiency load balancing algorithms critically depends nature tasks.therefore information tasks available time decision making greater potential optimization.size tasks perfect knowledge execution time tasks allows reach optimal load distribution see algorithm prefix sum.unfortunately fact idealized case.knowing exact execution time task extremely rare situation.for reason several techniques get idea different execution times.
Load balancing (computing)	first fortunate scenario tasks relatively homogeneous size possible consider require approximately average execution time.hand execution time irregular sophisticated techniques must used.one technique add metadata task.depending previous execution time similar metadata possible make inferences future task based statistics.dependencies cases tasks depend other.
Load balancing (computing)	interdependencies illustrated directed acyclic graph.intuitively tasks cannot begin others completed.assuming required time tasks known advance optimal execution order must lead minimization total execution time.although nphard problem therefore difficult solved exactly.algorithms like job scheduler calculate optimal task distributions using metaheuristic methods.segregation tasks another feature tasks critical design load balancing algorithm ability broken subtasks execution.
Load balancing (computing)	treeshaped computation algorithm presented later takes great advantage specificity.static dynamic algorithms static load balancing algorithm static take account state system distribution tasks.thereby system state includes measures load level sometimes even overload certain processors.instead assumptions overall system made beforehand arrival times resource requirements incoming tasks.addition number processors respective power communication speeds known.
Load balancing (computing)	therefore static load balancing aims associate known set tasks available processors order minimize certain performance function.trick lies concept performance function.static load balancing techniques commonly centralized around router master distributes loads optimizes performance function.minimization take account information related tasks distributed derive expected execution time.the advantage static algorithms easy set extremely efficient case fairly regular tasks processing http requests website.however still statistical variance assignment tasks lead overloading computing units.dynamic unlike static load distribution algorithms dynamic algorithms take account current load computing units also called nodes system.
Load balancing (computing)	approach tasks moved dynamically overloaded node underloaded node order receive faster processing.algorithms much complicated design produce excellent results particular execution time varies greatly one task another.dynamic load balancing architecture modular since mandatory specific node dedicated distribution work.tasks uniquely assigned processor according state given moment unique assignment.hand tasks permanently redistributed according state system evolution called dynamic assignment.obviously load balancing algorithm requires much communication order reach decisions runs risk slowing resolution overall problem.
Load balancing (computing)	hardware architecture heterogenous machines parallel computing infrastructures often composed units different computing power taken account load distribution.for example lowerpowered units may receive requests require smaller amount computation case homogeneous unknown request sizes receive fewer requests larger units.shared distributed memory parallel computers often divided two broad categories processors share single common memory read write parallel pram model computing unit memory distributed memory model information exchanged messages.for sharedmemory computers managing write conflicts greatly slows speed individual execution computing unit.however work perfectly well parallel.conversely case message exchange processors work full speed.hand comes collective message exchange processors forced wait slowest processors start communication phase.in reality systems fall exactly one categories.
Load balancing (computing)	general processors internal memory store data needed next calculations organized successive clusters.often processing elements coordinated distributed memory message passing.therefore load balancing algorithm uniquely adapted parallel architecture.otherwise risk efficiency parallel problem solving greatly reduced.hierarchy adapting hardware structures seen two main categories load balancing algorithms.
Load balancing (computing)	one hand one tasks assigned “master” executed “workers” keep master informed progress work master take charge assigning reassigning workload case dynamic algorithm.literature refers masterworker architecture.hand control distributed different nodes.load balancing algorithm executed responsibility assigning tasks well reassigning splitting appropriate shared.last category assumes dynamic load balancing algorithm.since design load balancing algorithm unique previous distinction must qualified.
Load balancing (computing)	thus also possible intermediate strategy example master nodes subcluster subject global master.also multilevel organizations alternation masterslave distributed control strategies.latter strategies quickly become complex rarely encountered.designers prefer algorithms easier control.adaptation larger architectures scalability context algorithms run long term servers cloud... computer architecture evolves time.
Load balancing (computing)	however preferable design new algorithm time.an extremely important parameter load balancing algorithm therefore ability adapt scalable hardware architecture.called scalability algorithm.algorithm called scalable input parameter performance remains relatively independent size parameter.when algorithm capable adapting varying number computing units number computing units must fixed execution called moldable.hand algorithm capable dealing fluctuating amount processors execution algorithm said malleable.load balancing algorithms least moldable.
Load balancing (computing)	fault tolerance especially largescale computing clusters tolerable execute parallel algorithm cannot withstand failure one single component.therefore fault tolerant algorithms developed detect outages processors recover computation.approaches static distribution full knowledge tasks prefix sum tasks independent respective execution time tasks subdivided simple optimal algorithm.by dividing tasks way give amount computation processor remains done group results together.using prefix sum algorithm division calculated logarithmic time respect number processors.if however tasks cannot subdivided i.e.atomic although optimizing task assignment difficult problem still possible approximate relatively fair distribution tasks provided size much smaller total computation performed nodes.most time execution time task unknown rough approximation available.
Load balancing (computing)	algorithm although particularly efficient viable scenarios.static load distribution without prior knowledge even execution time known advance static load distribution always possible.roundrobin scheduling roundrobin algorithm first request sent first server next second last.started assigning next request first server on.this algorithm weighted powerful units receive largest number requests receive first.randomized static randomized static load balancing simply matter randomly assigning tasks different servers.
Load balancing (computing)	method works quite well.hand number tasks known advance even efficient calculate random permutation advance.avoids communication costs assignment.longer need distribution master every processor knows task assigned it.even number tasks unknown still possible avoid communication pseudorandom assignment generation known processors.the performance strategy measured total execution time given fixed set tasks decreases maximum size tasks.
Load balancing (computing)	others course methods assignment well less work assign tasks servers performing less method also weighted.hash allocates queries according hash table.power two choices pick two servers random choose better two options.masterworker scheme masterworker schemes among simplest dynamic load balancing algorithms.master distributes workload workers also sometimes referred slaves.initially workers idle report master.master answers worker requests distributes tasks them.

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