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February17,2010

TechnicalInterviewQuestions(Part1/3)[Networking]Edited&MaintainedbySYEDJAHANZAIB/[email protected]

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TechnicalInterviewQuestions(Part1/3)[Networking]

Edited&MaintainedbySYEDJAHANZAIB/[email protected]

1.WhatisanIPaddress?

2.Whatisasubnetmask?

3.WhatisARP?

4.WhatisARPCachePoisoning?

5.WhatistheANDingprocess?

6.Whatisadefaultgateway?WhathappensifIdonthaveone?

7.CanaworkstationcomputerbeconfiguredtobrowsetheInternetandyetNOThaveadefaultgateway?

8.Whatisasubnet?

9.WhatisAPIPA?



10.WhatisanRFC?Nameafewifpossible(notnecessarilythenumbers,justtheideasbehindthem)

11.WhatisRFC1918?

12.WhatisCIDR?

13.YouhavethefollowingNetworkID:192.115.103.64/27.WhatistheIPrangeforyournetwork?

14.YouhavethefollowingNetworkID:131.112.0.0.Youneedatleast500hostspernetwork.Howmanynetworkscanyoucreate?Whatsubnetmaskwillyouuse?

15.Youneedtoviewatnetworktraffic.Whatwillyouuse?Nameafewtools

16.HowdoIknowthepaththatapackettakestothedestination?

17.Whatdoestheping192.168.0.1l1000n100commanddo?

18.WhatisDHCP?Whatarethebenefitsanddrawbacksofusingit?

19.DescribethestepstakenbytheclientandDHCPserverinordertoobtainanIPaddress.

20.WhatistheDHCPNACKandwhendoIgetone?Name2scenarios.

21.WhatportsareusedbyDHCPandtheDHCPclients?

22.DescribetheprocessofinstallingaDHCPserverinanADinfrastructure.

23.WhatisDHCPINFORM?

24.DescribetheintegrationbetweenDHCPandDNS.

25.WhatoptionsinDHCPdoyouregularlyuseforanMSNetwork?

26.WhatareUserClassesandVendorClassesinDHCP?

27.HowdoIconfigureaclientmachinetouseaspecificUserClass?

28.WhatistheBOOTPprotocolusedfor,wheremightyoufinditinwindowsnetworkinfrastructure?

29.DNSzonesdescribethedifferencesbetweenthe4types.

30.DNSrecordtypesdescribethemostimportantones.

31.Describetheprocessofworkingwithanexternaldomainname

32.DescribetheimportanceofDNStoAD.



33.DescribeafewmethodsoffindinganMXrecordforaremotedomainontheInternet.

34.WhatdoesDisableRecursioninDNSmean?

35.WhatcouldcausetheForwardersandRootHintstobegrayedout?

36.WhatisaSingleLabeldomainnameandwhatsortofissuescanitcause?

37.Whatistheinaddr.arpazoneusedfor?

38.WhataretherequirementsfromDNStosupportAD?

39.HowdoyoumanuallycreateSRVrecordsinDNS?

40.Name3benefitsofusingADintegratedzones.

41.WhatarethebenefitsofusingWindows2003DNSwhenusingADintegratedzones?

42.YouinstalledanewADdomainandthenew(andfirst)DChasnotregistereditsSRVrecordsinDNS.Nameafewpossiblecauses.

43.WhatarethebenefitsandscenariosofusingStubzones?

44.WhatarethebenefitsandscenariosofusingConditionalForwarding?

45.WhatarethedifferencesbetweenWindowsClustering,NetworkLoadBalancingandRoundRobin,andscenariosforeachuse?

46.HowdoIworkwiththeHostnamecacheonaclientcomputer?

47.HowdoIcleartheDNScacheontheDNSserver?

48.Whatisthe224.0.1.24addressusedfor?

49.WhatisWINSandwhendoweuseit?

50.CanyouhaveaMicrosoftbasednetworkwithoutanyWINSserveronit?WhataretheconsiderationsregardingnotusingWINS?

51.DescribethedifferencesbetweenWINSpushandpullreplications.

52.WhatisthedifferencebetweentombstoningaWINSrecordandsimplydeletingit?

53.NametheNetBIOSnamesyoumightexpectfromaWindows2003DCthatisregisteredinWINS.

54.Describetheroleoftheroutingtableonahostandonarouter.

55.Whatareroutingprotocols?Whydoweneedthem?Nameafew.

56.Whatarerouterinterfaces?Whattypescantheybe?



57.InWindows2003routing,whataretheinterfacefilters?

58.WhatisNAT?

59.WhatistherealdifferencebetweenNATandPAT?

60.HowdoyouconfigureNATonWindows2003?

61.HowdoyouallowinboundtrafficforspecifichostsonWindows2003NAT?

62.WhatisVPN?WhattypesofVPNdoesWindows2000andbeyondworkwithnatively?

63.WhatisIAS?Inwhatscenariosdoweuseit?

64.WhatsthedifferencebetweenMixedmodeandNativemodeinADwhendealingwithRRAS?

65.WhatistheRASandIASgroupinAD?

66.WhatareConditionsandProfileinRRASPolicies?

67.WhattypesorauthenticationcanaWindows2003basedRRASworkwith?68.HowdoesSSLwork?

69.HowdoesIPSecwork?

70.HowdoIdeployIPSecforalargenumberofcomputers?

71.WhattypesofauthenticationcanIPSecuse?

72.WhatisPFS(PerfectForwardSecrecy)inIPSec?

73.HowdoImonitorIPSec?

74.LookingatIPSecencryptedtrafficwithasniffer.WhatpackettypesdoIsee?

75.WhatcanyoudowithNETSH?

76.HowdoIlookattheopenportsonmymachine?

ANSWERS



1)WhatisanIPaddress?

AnInternetProtocol(IP)addressisanumericallabelthatisassignedtodevicesparticipatinginacomputernetworkutilizingtheInternet

anIPaddressisa32bitnumberthatidentifieseachsenderorreceiverofinformationthatissentinpacketsacrossthelan/Internet.

AnIPaddresshastwoparts:theidentifierofaparticularnetworkontheInternetandanidentifieroftheparticulardevice(whichcanbeaserveroraworkstation)withinthatnetwork.OntheInternetitselfthatis,betweentherouterthatmovepacketsfromonepointtoanotheralongtherouteonlythenetworkpartoftheaddressislookedat.

2)Whatisasubnetmask?

AsubnetmaskallowsyoutoidentifywhichpartofanIPaddressisreservedforthenetwork,andwhichpartisavailableforhostuse.IfyoulookattheIPaddressalone,especiallynowwithclasslessinterdomainrouting,youcanttellwhichpartoftheaddressiswhich.Addingthesubnetmask,ornetmask,givesyoualltheinformationyouneedtocalculatenetworkandhostportionsoftheaddresswithease.Insummary,knowingthesubnetmaskcanallowyoutoeasilycalculatewhetherIPaddressesareon.Subnettingenablesthenetworkadministratortofurtherdividethehostpartoftheaddressintotwoormoresubnets.

3)WhatisARP?

ShortforAddressResolutionProtocol,anetworklayerprotocolusedtoconvertanIPaddressintoaphysicaladdress(calledaDLCaddress),suchasanEthernetaddress.AhostwishingtoobtainaphysicaladdressbroadcastsanARPrequestontotheTCP/IPnetwork.ThehostonthenetworkthathastheIPaddressintherequestthenreplieswithitsphysicalhardwareaddress.

ARPisaveryimportantpartofIPnetworking.ARPisusedtoconnectOSILayer3(Network)toOSILayer2(DataLink).Formostofus,thatmeansthatARPisusedtolinkourIPaddressingtoourEthernetaddressing(MACAddressing).Foryoutocommunicatewithanydeviceonyournetwork,youmusthavetheEthernetMACaddressforthatdevice.IfthedeviceisnotonyourLAN,yougothroughyourdefaultgateway(yourrouter).Inthiscase,yourrouterwillbethedestinationMACaddressthatyourPCwillcommunicatewith.

4)WhatisARPCachePoisoning?amethodofattackinganEthernetLANbyupdatingthetargetcomputersARPcachewithbothaforgedARPrequestandreplypacketsinanefforttochangetheLayer2EthernetMACaddress(i.e.,theaddressofthenetworkcard)toonethattheattackercanmonitor.BecausetheARPreplieshavebeenforged,thetargetcomputersendsframesthatweremeantfortheoriginaldestinationtotheattackerscomputerfirstsotheframescanberead.AsuccessfulAPRattemptisinvisibletotheuser.ARPcachepoisoning,alsoknownasARPspoofing,istheprocessoffalsifyingthesourceMediaAccessControl(MAC)addressesofpacketsbeingsentonanEthernetnetwork.ItisaMAClayerattackthatcanonlybecarriedoutwhenanattackerisconnectedtothesamelocalnetworkasthetargetmachines,limitingitseffectivenessonlytonetworksconnectedwithswitches,hubs,andbridges;notrouters.

5)WhatistheANDingprocess?

Inordertodeterminewhetheradestinationhostislocalorremote,acomputerwillperformasimple



mathematicalcomputationreferredtoasanANDoperation.Whilethesendinghostdoesthisoperationinternally,understandingwhattakesplaceisthekeytounderstandinghowanIPbasedsystemknowswhethertosendpacketsdirectlytoahostortoarouter.

NoticethatwhentheresultingANDvaluesareconvertedbacktobinary,itbecomesclearthatthetwohostsareondifferentnetworks.ComputerAisonsubnet192.168.56.0,whilethedestinationhostisonsubnet192.168.64.0,whichmeansthatComputerAwillnextbesendingthedatatoarouter.WithoutANDing,determininglocalandremotehostscanbedifficult.Onceyoureveryfamiliarwithsubnettingandcalculatingrangesofaddresses,recognizinglocalandremotehostswillbecomemuchmoreintuitive.Wheneveryoureindoubtastowhetherhostsarelocalorremote,usetheANDingprocess.YoushouldalsonoticethattheANDingprocessalwaysproducesthesubnetIDofagivenhost.

6)Whatisadefaultgateway?WhathappensifIdonthaveone?

AdefaultgatewayisusedbyahostwhenanIPpacketsdestinationaddressbelongstosomeplaceoutsidethelocalsubnet.ThedefaultgatewayaddressisusuallyaninterfacebelongingtotheLANsborderrouter.Incomputernetworking,adefaultnetworkgatewayisthedevicethatpassestrafficfromthelocalsubnettodevicesonothersubnets.ThedefaultgatewayoftenconnectsalocalnetworktotheInternet,althoughinternalgatewaysforconnectingtwolocalnetworksalsoexist.

7)CanaworkstationcomputerbeconfiguredtobrowsetheInternetandyetNOThaveadefaultgateway?

Ifweareusingpublicipaddress,wecanbrowsetheinternet.Ifitishavinganintranetaddressagatewayisneededasarouterorfirewalltocommunicatewithinternet.

8)Whatisasubnet?

Aportionofanetworkwhichsharesanetworkaddressinwhicheachcomponentisidentifiedbyasubnetnumber.Asubnetisalogicalorganizationofnetworkaddressrangesusedtoseparatehostsandnetworkdevicesfromeachothertoserveadesignpurpose.Inmanycases,subnetsarecreatedtoserveasphysicalorgeographicalseparationssimilartothosefoundbetweenrooms,floors,buildings,orcities.

9)WhatisAPIPA?

ShortforAutomaticPrivateIPAddressing,afeatureoflaterWindowsoperatingsystems.WithAPIPA,DHCPclientscanautomaticallyselfconfigureanIPaddressandsubnetmaskwhenaDHCPserverisntavailable.WhenaDHCPclientbootsup,itfirstlooksforaDHCPserverinordertoobtainanIPaddressandsubnetmask.Iftheclientisunabletofindtheinformation,itusesAPIPAtoautomaticallyconfigureitselfwithanIPaddressfromarangethathasbeenreservedespeciallyforMicrosoft.TheIPaddressrangeis169.254.0.1through169.254.255.254.TheclientalsoconfiguresitselfwithadefaultclassBsubnetmaskof255.255.0.0.AclientusestheselfconfiguredIPaddressuntilaDHCPserverbecomesavailable.

TheAPIPAservicealsochecksregularlyforthepresenceofaDHCPserver(everyfiveminutes,accordingtoMicrosoft).IfitdetectsaDHCPserveronthenetwork,APIPAstops,andtheDHCPserverreplacestheAPIPAnetworkingaddresseswithdynamicallyassignedaddresses.

APIPAismeantfornonroutedsmallbusinessenvironments,



usuallylessthan25clients.

10)WhatisanRFC?Nameafewifpossible(notnecessarilythenumbers,justtheideasbehindthem)

ShortforRequestforComments,aseriesofnotesabouttheInternet,startedin1969(whentheInternetwastheARPANET).AnInternetDocumentcanbesubmittedtotheIETFbyanyone,buttheIETFdecidesifthedocumentbecomesanRFC.Eventually,ifitgainsenoughinterest,itmayevolveintoanInternetstandard.EachRFCisdesignatedbyanRFCnumber.Oncepublished,anRFCneverchanges.ModificationstoanoriginalRFCareassignedanewRFCnumber.

11)WhatisRFC1918?

RFC1918isAddressAllocationforPrivateInternetsTheInternetAssignedNumbersAuthority(IANA)hasreservedthefollowingthreeblocksoftheIPaddressspaceforprivateinternets:10.0.0.010.255.255.255(10/8prefix)172.16.0.0172.31.255.255(172.16/12prefix)192.168.0.0192.168.255.255(192.168/16prefix)Wewillrefertothefirstblockas24bitblock,thesecondas20bitblock,andtothethirdas16bitblock.Notethat(inpreCIDRnotation)thefirstblockisnothingbutasingleclassAnetworknumber,whilethesecondblockisasetof16contiguousclassBnetworknumbers,andthirdblockisasetof256contiguousclassCnetworknumbers.

12)WhatisCIDR?

CIDR(ClasslessInterDomainRouting,sometimesknownassupernetting)isawaytoallocateandspecifytheInternetaddressesusedininterdomainroutingmoreflexiblythanwiththeoriginalsystemofInternetProtocol(IP)addressclasses.Asaresult,thenumberofavailableInternetaddresseshasbeengreatlyincreased.

13.YouhavethefollowingNetworkID:192.115.103.64/27.WhatistheIPrangeforyournetwork?

Itrangesfrom192.115.103.64192.115.103.96

Buttheusableaddressarefrom192.115.103.64192.115.103.94

192.115.103.95itisthebroadcastaddress192.115.103.96willbetheipaddressofnextrange

wecanuse30hostsinthisnetwork

14.YouhavethefollowingNetworkID:131.112.0.0.Youneedatleast500hostspernetwork.Howmanynetworkscanyoucreate?Whatsubnetmaskwillyouuse?

Ifyouneed500usersthen2^9thwouldgiveyou512(rememberthefirstandlastarenetworkandbroadcast),510usable.Soofyour32bitsyouwouldturnthelast9offforhostandthatwouldgiveyougiveyoua255.255.254.0subnetmask(11111111.11111111.11111110.00000000).Nowthatweknowthatwecanseethatyouhavethefirst7ofyourthirdoctetturnedonsotofigureouthowmanysubnetsyouhaveustheformula



2^7th=128.Soyoucanhave128subnetswith500peopleonthem.

15.Youneedtoviewatnetworktraffic.Whatwillyouuse?Nameafewtools

winsharkortcpdump,orethereal(availableinourfileserver)

16.HowdoIknowthepaththatapackettakestothedestination?

usetracertcommandline

17.Whatdoestheping192.168.0.1l1000n100commanddo?

Thepingcommandwillsendroundtrippacketstoadestination(otherPC,router,printer,etc.)andseehowlongittakes.The192.168.0.1isthedestination(which,bythewayisatypicaldefaultIPaddressofarouter.)Thel1000ishowbigthepacketshouldbeinbytes.Thedefaultis32,ifthelparameterisnotused.Andthen100issayingtosendit100times.Thedefaultis4,whenthisparameterisnotused.

18.WhatisDHCP?Whatarethebenefitsanddrawbacksofusingit?

Benefits:

1.DHCPminimizesconfigurationerrorscausedbymanualIPaddressconfiguration.

2.Reducednetworkadministration.

Disadvantage

YourmachinenamedoesnotchangewhenyougetanewIPaddress.TheDNS(DomainNameSystem)nameisassociatedwithyourIPaddressandthereforedoeschange.ThisonlypresentsaproblemifotherclientstrytoaccessyourmachinebyitsDNSname.

19.DescribethestepstakenbytheclientandDHCPserverinordertoobtainanIPaddress.

*AtleastoneDHCPservermustexistonanetwork.OncetheDHCPserversoftwareisinstalled,youcreateaDHCPscope,whichisapoolofIPaddressesthattheservermanages.Whenclientslogon,theyrequestanIPaddressfromtheserver,andtheserverprovidesanIPaddressfromitspoolofavailableaddresses.*DHCPwasoriginallydefinedinRFC1531(DynamicHostConfigurationProtocol,October1993)butthemostrecentupdateisRFC2131(DynamicHostConfigurationProtocol,March1997).TheIETFDynamicHostConfiguration(dhc)WorkingGroupischarteredtoproduceaprotocolforautomatedallocation,configuration,andmanagementofIPaddressesandTCP/IPprotocolstackparameters.

20.WhatistheDHCPNACKandwhendoIgetone?Name2scenarios.

RecentlyIsawalotofqueriesregardingwhentheMicrosoftDHCPserverissuesaNAKtoDHCPclients.Forsimplificationpurposes,IamlistingdownthepossiblescenariosinwhichtheservershouldNOTissueaNAK.ThisshouldgiveyouagoodunderstandingofDHCPNAKbehavior.WhenaDHCPserverreceivesaDHCPRequestwithapreviouslyassignedaddressspecified,itfirstcheckstoseeifitcamefromthelocalsegmentbycheckingtheGIADDRfield.Ifitoriginatedfromthelocalsegment,the



DHCPservercomparestherequestedaddresstotheIPaddressandsubnetmaskbelongingtothelocalinterfacethatreceivedtherequest.DHCPserverwillissueaNAKtotheclientONLYIFitissurethattheclient,onthelocalsubnet,isaskingforanaddressthatdoesntexistonthatsubnet.TheserverwillsendaNAKEXCEPTinthefollowingscenarios:

1.Requestedaddressfrompossiblythesamesubnetbutnotintheaddresspooloftheserver:Thiscanbethefailoverscenarioinwhich2DHCPserversareservingthesamesubnetsothatwhenonegoesdown,theothershouldnotNAKtoclientswhichgotanIPfromthefirstserver.

2.Requestedaddressonadifferentsubnet:IftheAddressisfromthesamesuperscopetowhichthesubnetbelongs,DHCPserverwillACKtheREQUEST.

21.WhatportsareusedbyDHCPandtheDHCPclients?

RequestsareonUDPport68,ServerrepliesonUDP67

22.DescribetheprocessofinstallingaDHCPserverinanADinfrastructure.

UseAdd/Removeprogramwizard...

23.WhatisDHCPINFORM?

DHCPInformisaDHCPmessageusedbyDHCPclientstoobtainDHCPoptions.WhilePPPremoteaccessclientsdonotuseDHCPtoobtainIPaddressesfortheremoteaccessconnection,Windows2000andWindows98remoteaccessclientsusetheDHCPInformmessagetoobtainDNSserverIPaddresses,WINSserverIPaddresses,andaDNSdomainname.TheDHCPInformmessageissentaftertheIPCPnegotiationisconcluded.TheDHCPInformmessagereceivedbytheremoteaccessserveristhenforwardedtoaDHCPserver.TheremoteaccessserverforwardsDHCPInformmessagesonlyifithasbeenconfiguredwiththeDHCPRelayAgent..

24.DescribetheintegrationbetweenDHCPandDNS.

Traditionally,DNSandDHCPservershavebeenconfiguredandmanagedoneatatime.Similarly,changingauthorizationrightsforaparticularuseronagroupofdeviceshasmeantvisitingeachoneandmakingconfigurationchanges.DHCPintegrationwithDNSallowstheaggregationofthesetasksacrossdevices,enablingacompanysnetworkservicestoscaleinstepwiththegrowthofnetworkusers,devices,andpolicies,whilereducingadministrativeoperationsandcosts.

Thisintegrationprovidespracticaloperationalefficienciesthatlowertotalcostofownership.CreatingaDHCPnetworkautomaticallycreatesanassociatedDNSzone,forexample,reducingthenumberoftasksrequiredofnetworkadministrators.AndintegrationofDNSandDHCPinthesamedatabaseinstanceprovidesunmatchedconsistencybetweenserviceandmanagementviewsofIPaddresscentricnetworkservicesdata.

25.WhatoptionsinDHCPdoyouregularlyuseforanMSnetwork?

AutomaticprovidingIPaddress

Subnetmask

DNSserver



Domainname

Defaultgetawayorrouter

26.WhatareUserClassesandVendorClassesinDHCP?

MicrosoftVendorClassesThefollowinglistcontainspredefinedvendorclassesthatareavailableinWindows2000DHCPserver.

ClassDataClassNameDescriptionMSFT5.0MicrosoftWindows2000optionsClassthatincludesallWindows2000DHCPclients.MSFT98MicrosoftWindows98optionsClassthatincludesallWindows98andMicrosoftWindowsMillenniumEdition(Me)DHCPclients.MSFTMicrosoftoptionsClassthatincludesallWindows98,WindowsMe,andWindows2000DHCPclients.IfyouhavenonMicrosoftDHCPclients,youcandefineothervendorspecificclassesontheDHCPserver.Whenyoudefinesuchclasses,makesurethevendorclassidentifierthatyoudefinematchestheidentifierusedbytheclients.

UserClasses

ThefollowinglistcontainspredefineduserclassesthatareavailableinWindows2000DHCPserver.

CollapsethistableExpandthistable

ClassIDClassTypeDescriptionUnspecifiedDefaultuserclassAllDHCPclientsthathavenouserclassspecified.RRAS.MicrosoftDefaultRoutingandRemoteAccessclassAllDialUpNetworking(DUN)clients.BootpDefaultBootpclassAllBootpclients

Inadditiontothesepredefinedclasses,youcanalsoaddcustomuserclassesforWindows2000DHCPclients.Whenyouconfiguresuchclasses,youmustspecifyacustomidentifierthatcorrespondstotheuserclassdefinedontheDHCPserver.

27.HowdoIconfigureaclientmachinetouseaspecificUserClass?

Thecommandtoconfigureaclientmachinetouseaspecificuserclassis

ipconfig/setclassid

Eg:

ipconfig/setclassidLocalAreaNetworkAccounting

28.WhatistheBOOTPprotocolusedfor,wheremightyoufinditinWindowsnetworkinfrastructure?

BootP(RFC951)provides



*auniqueIPaddresstotherequester(usingport67)similartotheDHCPrequestonport68AND*canprovide(wheresupported)theabilitytobootasystemwithoutaharddrive(ie:adisklessclient)

AppleOSX10.*ServersupportsBootP(albeit)renamedasNetBoot.ThefacilityallowstheAdmintomaintainaselectedsetofconfigurationsasbootimagesandthenassignsetsofclientsystemstoshare(orbootfrom)thatimage.ForexampleAccounting,Management,andEngineeringdepartmentshaveelementsincommon,butwhichcanbeuniquefromotherdepartments.Performingupgradesandmaintenanceonthreeimagesisfarmoreproductivethatworkingonallclientsystemsindividually.

Startupisobviouslynetworkintensive,andbeyond4050clients,theAdminneedstocarefullysubnettheinfrastructure,usegigabitswitches,andhosttheimageslocaltotheclientstoavoidsaturatingthenetwork.ThiswillexpandthenumberofBootPserversandmultiplythenumberofimages,buttheproductivityof1BootPserverper50clientsisundeniable

Sunmicro,Linux,andAIXRS/600allsupportBootP.

Todate,Windowsdoesnotsupportbootingdisklessclients.

29.DNSzonesdescribethedifferencesbetweenthe4types.

Dnszoneisactualfilewhichcontainsalltherecordsforaspecificdomain.

i)ForwardLookupZones:

Thiszoneisresponsibletoresolvehostnametoip.

ii)ReverseLookupZones:

Thiszoneisresponsibletoresolveiptohostname.

iii)StubZone:

Stubzoneisreadonlycopyofprimaryzone.butitcontainsonly3recordsviz

theSOAfortheprimaryzone,NSrecordandaHost(A)record.

30.DNSrecordtypesdescribethemostimportantones.TypeofRecordWhatitdoes

A(Host)Classicresourcerecord.MapshostnametoIP(ipv4)

PTRMapsIPtohostname(ReverseofA(Host)

AAAAMapshostnametoip(ipv6)

CnameCanonicalname,inplainEnglishanalias.suchasWebServer,FTPServer,ChatServer

NSIdentifiesDNSnameservers.Importantforforwarders

MXMailservers,particularlyforotherdomains.MXrecordsrequiredtodeliverinternetemail.



_SRVRequiredforActiveDirectory.Wholefamilyofunderscoreservice,records,forexample,gc=globalcatalog.

SOAMakeapointoffindingtheStartofAuthority(SOA)tabattheDNSServer.

31.Describetheprocessofworkingwithanexternaldomainname

ServingSiteswithExternalDomainNameServers,IfyouhostWebsitesonthisserverandhaveastandaloneDNSserveractingasaprimary(master)nameserverforyoursites,youmaywanttosetupyourcontrolpanelsDNSservertofunctionasasecondary(slave)nameserver:

TomakethecontrolpanelsDNSserveractasasecondarynameserver:

1.GotoDomains>domainname>DNSSettings(intheWebSitegroup).2.ClickSwitchDNSServiceMode.3.SpecifytheIPaddressoftheprimary(master)DNSserver.4.ClickAdd.5.Repeatstepsfrom1to5foreachWebsitethatneedstohaveasecondarynameserveronthismachine.

TomakethecontrolpanelsDNSserveractasaprimaryforazone:

1.GotoDomains>domainname>DNSSettings(intheWebSitegroup).2.ClickSwitchDNSServiceMode.Theoriginalresourcerecordsforthezonewillberestored.

IfyouhostWebsitesonthisserverandrelyentirelyonothermachinestoperformtheDomainNameServiceforyoursites(therearetwoexternalnameserversaprimaryandasecondary),switchoffthecontrolpanelsDNSserviceforeachsiteservedbyexternalnameservers.

ToswitchoffthecontrolpanelsDNSserviceforasiteservedbyanexternalnameserver:

1.GotoDomains>domainname>DNSSettings(intheWebSitegroup).2.ClickSwitchOfftheDNSServiceintheToolsgroup.TurningtheDNSserviceoffforthezonewillrefreshthescreen,sothatonlyalistofnameserversremains.

Note:Thelistednameserverrecordshavenoeffectonthesystem.Theyareonlypresentedonthescreenasclickablelinkstogiveyouachancetovalidatetheconfigurationofthezonemaintainedontheexternalauthoritativenameservers.

1.Repeatthestepsfrom1to3toswitchoffthelocaldomainnameserviceforeachsiteservedbyexternalnameservers.

Ifyouwishtovalidatetheconfigurationofazonemaintainedonauthoritativenameservers:

1.GotoDomains>domainname>DNSSettings(intheWebSitegroup).2.Addtothelisttheentriespointingtotheappropriatenameserversthatareauthoritativeforthezone:clickAdd,specifyanameserver,andclickOK.Repeatthisforeachnameserveryouwouldliketotest.Therecordswillappearinthelist.

1.Clicktherecordsthatyouhavejustcreated.ParallelsPleskPanelwillretrievethezonefilefroma



remotenameserverandchecktheresourcerecordstomakesurethatdomainsresourcesareproperlyresolved.

Theresultswillbeinterpretedanddisplayedonthescreen.

32.DescribetheimportanceofDNStoAD.

WhenyouinstallActiveDirectoryonaserver,youpromotetheservertotheroleofadomaincontrollerforaspecifieddomain.Whencompletingthisprocess,youarepromptedtospecifyaDNSdomainnamefortheActiveDirectorydomainforwhichyouarejoiningandpromotingtheserver.Ifduringthisprocess,aDNSserverauthoritativeforthedomainthatyouspecifiedeithercannotbelocatedonthenetworkordoesnotsupporttheDNSdynamicupdateprotocol,youarepromptedwiththeoptiontoinstallaDNSserver.ThisoptionisprovidedbecauseaDNSserverisrequiredtolocatethisserverorotherdomaincontrollersformembersofanActiveDirectorydomain

33.DescribeafewmethodsoffindinganMXrecordforaremotedomainontheInternet.

InordertofindMXRecordsforSMTPdomainsyoucanuseCommandlinetoolssuchasNSLOOKUPorDIG.Youcanalsouseonlinewebservicesthatallowyoutoperformquicksearchesanddisplaytheinformationinaconvenientmanner.

34.WhatdoesDisableRecursioninDNSmean?

IntheWindows2000/2003DNSconsole(dnsmgmt.msc),underaserversProperties>ForwarderstabisthesettingDonotuserecursionforthisdomain.OntheAdvancedtabyouwillfindtheconfusinglysimilaroptionDisablerecursion(alsodisablesforwarders).

RecursionreferstotheactionofaDNSserverqueryingadditionalDNSservers(e.g.localISPDNSortherootDNSservers)toresolvequeriesthatitcannotresolvefromitsowndatabase

35.WhatcouldcausetheForwardersandRootHintstobegrayedout?

Win2KconfiguredyourDNSserverasaprivaterootserver

36.WhatisaSingleLabeldomainnameandwhatsortofissuescanitcause?

Singlelabelnamesconsistofasinglewordlikecontoso.SinglelabelDNSnamescannotberegisteredbyusinganInternetregistrar.ClientcomputersanddomaincontrollersthatjoinedtosinglelabeldomainsrequireadditionalconfigurationtoynamicallyregisterDNSrecordsinsinglelabelDNSzones.ClientcomputersanddomaincontrollersmayrequireadditionalconfigurationtoresolveDNSqueriesinsinglelabelDNSzones.Bydefault,WindowsServer2003baseddomainmembers,WindowsXPbaseddomainmembers,andWindows2000baseddomainmembersdonotperformdynamicupdatestosinglelabelDNSzones.Someserverbasedapplicationsareincompatiblewithsinglelabeldomainnames.Applicationsupportmaynotexistintheinitialreleaseofanapplication,orsupportmaybedroppedinafuturerelease.Forexample,MicrosoftExchangeServer2007isnotsupportedinenvironmentsinwhichsinglelabelDNSisused.SomeserverbasedapplicationsareincompatiblewiththedomainrenamefeaturethatissupportedinWindowsServer2003domaincontrollersandinWindowsServer2008domaincontrollers.TheseincompatibilitieseitherblockorcomplicatetheuseofthedomainrenamefeaturewhenyoutrytorenameasinglelabelDNSnametoafullyqualifieddomainname.



37.Whatistheinaddr.arpazoneusedfor?

WhencreatingDNSrecordsforyourhosts,Arecordsmakesense.Afterall,howcantheworldfindyourmailserverunlesstheIPaddressofthatserverisassociatedwithitshostnamewithinaDNSdatabase?However,PTRrecordsarentaseasilyunderstood.Ifyoualreadyhaveazonefile,whydoestherehavetobeaseparateinaddr.arpazonecontainingPTRrecordsmatchingyourArecords?AndwhoshouldbemakingthosePTRrecordsyouoryourprovider?Letsstartbydefininginaddr.arpa..arpaisactuallyaTLDlike.comor.org.ThenameoftheTLDcomesfromAddressandRoutingParameterAreaandithasbeendesignatedbytheIANAtobeusedexclusivelyforInternetinfrastructurepurposes.Inotherwords,itisanimportantzoneandanintegralpartoftheinnerworkingsofDNS.TheRFCforDNS(RFC1035)hasanentiresectionontheinaddr.arpadomain.Thefirsttwoparagraphsinthatsectionstatethepurposeofthedomain:TheInternetusesaspecialdomaintosupportgatewaylocationandInternetaddresstohostmapping.Otherclassesmayemployasimilarstrategyinotherdomains.Theintentofthisdomainistoprovideaguaranteedmethodtoperformhostaddresstohostnamemapping,andtofacilitatequeriestolocateallgatewaysonaparticularnetworkintheInternet.Notethatbothoftheseservicesaresimilartofunctionsthatcouldbeperformedbyinversequeries;thedifferenceisthatthispartofthedomainnamespaceisstructuredaccordingtoaddress,andhencecanguaranteethattheappropriatedatacanbelocatedwithoutanexhaustivesearchofthedomainspace.Inotherwords,thiszoneprovidesadatabaseofallallocatednetworksandtheDNSreachablehostswithinthosenetworks.Ifyourassignednetworkdoesnotappearinthiszone,itappearstobeunallocated.AndifyourhostsdonthaveaPTRrecordinthisdatabase,theyappeartobeunreachablethroughDNS.AssuminganArecordexistsforahost,amissingPTRrecordmayormaynotimpactontheDNSreachabilityofthathost,dependingupontheapplicationsrunningonthathost.Forexample,amailserverwilldefinitelybeimpactedasPTRrecordsareusedinmailheaderchecksandbymostantiSPAMmechanisms.Dependinguponyourwebserverconfiguration,itmayalsodependuponanexistingPTRrecord.ThisiswhytheDNSRFCsrecommendthateveryArecordhasanassociatedPTRrecord.ButwhoshouldmakeandhostthosePTRrecords?TwentyyearsagowhenyoucouldbuyafullClassCnetworkaddress(i.e.254hostaddresses)theanswerwaseasy:you.Remember,theinaddr.arpazoneisconcernedwithdelegatednetworkaddresses.Inotherwords,theownerofthenetworkaddressisauthoritative(i.e.responsible)forthehostPTRrecordsassociatedwiththatnetworkaddressspace.Ifyouonlyownoneortwohostaddresseswithinanetworkaddressspace,theprovideryoupurchasedthoseaddressesfromneedstohostyourPTRrecordsastheprovideristheownerof(i.e.authoritativefor)thenetworkaddress.ThingsareabitmoreinterestingifyouhavebeendelegatedaCIDRblockofaddresses.Theinaddr.arpazoneassumesaclassfuladdressingschemewhereaClassAaddressisoneoctet(or/8),aClassBis2octets(or/16)andaClassCis3octets(or/24).CIDRallowsfordelegatingaddressspaceoutsideoftheseboundariessaya/19ora/28.RFC2317providesabestcurrentpracticeformaintaininginaddr.arpawiththesetypesofnetworkallocations.HereisasummaryregardingPTRrecords:DontwaituntiluserscomplainaboutDNSunreachabilitybeproactiveandensurethereisanassociatedPTRrecordforeveryArecord.IfyourproviderhostsyourArecords,theyshouldalsohostyourPTRrecords.IfyouonlyhaveoneortwoassignedIPaddresses,yourprovidershouldhostyourPTRrecordsastheyareauthoritativeforthenetworkthosehostsbelongto.Ifyouownanentirenetworkaddress(e.g.aClassCaddressendingin0),youareresponsibleforhostingyourPTRrecords.IfyouareconfiguringaninternalDNSserverwithintheprivateaddressranges(e.g.10.0.0.0or192.168.0.0),youareresponsibleforyourowninternalPTRrecords.Remember:thekeytoPTRhostingisknowingwhoisauthoritativeforthenetworkaddressforyourdomain.Whenindoubt,itprobablyisnotyou.

38.WhataretherequirementsfromDNStosupportAD?WhenyouinstallActiveDirectoryonamemberserver,thememberserverispromotedtoadomaincontroller.ActiveDirectoryusesDNSasthelocationmechanismfordomaincontrollers,enablingcomputersonthenetworktoobtainIPaddressesofdomaincontrollers.Duringtheinstallationof



ActiveDirectory,theservice(SRV)andaddress(A)resourcerecordsaredynamicallyregisteredinDNS,whicharenecessaryforthesuccessfulfunctionalityofthedomaincontrollerlocator(Locator)mechanism.Tofinddomaincontrollersinadomainorforest,aclientqueriesDNSfortheSRVandADNSresourcerecordsofthedomaincontroller,whichprovidetheclientwiththenamesandIPaddressesofthedomaincontrollers.Inthiscontext,theSRVandAresourcerecordsarereferredtoasLocatorDNSresourcerecords.Whenaddingadomaincontrollertoaforest,youareupdatingaDNSzonehostedonaDNSserverwiththeLocatorDNSresourcerecordsandidentifyingthedomaincontroller.Forthisreason,theDNSzonemustallowdynamicupdates(RFC2136)andtheDNSserverhostingthatzonemustsupporttheSRVresourcerecords(RFC2782)toadvertisetheActiveDirectorydirectoryservice.FormoreinformationaboutRFCs,seeDNSRFCs.IftheDNSserverhostingtheauthoritativeDNSzoneisnotaserverrunningWindows2000orWindowsServer2003,contactyourDNSadministratortodetermineiftheDNSserversupportstherequiredstandards.Iftheserverdoesnotsupporttherequiredstandards,ortheauthoritativeDNSzonecannotbeconfiguredtoallowdynamicupdates,thenmodificationisrequiredtoyourexistingDNSinfrastructure.

39.HowdoyoumanuallycreateSRVrecordsinDNS?thisisonwindowsserver

gotorun>dnsmgmt.msc

rightclickonthezoneyouwanttoaddsrvrecordtoandchooseothernewrecordandchooseservicelocation(srv)..

40.Name3benefitsofusingADintegratedzones.

1.youcangiveeasynameresolutiontourclients.

2.BycreatingADintegratedzoneyoucanalsotracehackerandspammerbycreatingreversezone.

3.ADintegratedzonedallforincrementalzonetransferswhichontransferchangesandnottheentirezone.Thisreduceszonetransfertraffic.

4.ADIntegratedzonessuportbothsecureanddmanicupdates.

5.ADintegratedzonesarestoredaspartoftheactivedirectoryandsupportdomainwideorforestwidereplicationthroughapplicationpertitionsinAD.

41.WhatarethebenefitsofusingWindows2003DNSwhenusingADintegratedzones?

Advantages:

DNSsupportsDynamicregistrationofSRVrecordsregisteredbyaActiveDirectoryserveroradomaincontrollerduringpromotion.WiththehelpofSRVrecordsclientmachinescanfinddomaincontrollersinthenetwork.

1.DNSsupportsSecureDynamicupdates.Unauthorizedaccessisdenied.

2.ExchangeserverneedsinternalDNSorADDNStolocateGlobalCatalogservers.

3.ActiveDirectoryIntegratedZone.Ifyouhavemorethanonedomaincontroller(recommended)youneednotworryaboutzonereplication.ActiveDirectoryreplicationwilltakecareofDNSzonereplicationalso.



4.IfyournetworkuseDHCPwithActiveDirectorythennootherDHCPwillbeabletoserviceclientrequestscomingfromdifferentnetwork.ItisbecauseDHCPserverisauthorizedinADandwillbetheonlyservertoparticipateonnetworktoprovideIPAddressinformationtoclientmachines.

5.Moreover,youcanuseNT4DNSwithServicePack4orlater.ItsupportsbothSRVrecordregistrationandDynamicUpdates.

UsingMicrosoftDNSgivesthefollowingbenefits:Ifyouimplementnetworksthatrequiresecureupdates.IfyouwanttotakebenefitofActiveDirectoryreplication.IfyouwanttointegrateDHCPwithDNSforLowlevelclientstoregistertheirHostrecordsinZonedatabase.

42.YouinstalledanewADdomainandthenew(andfirst)DChasnotregistereditsSRVrecordsinDNS.Nameafewpossiblecauses.

ThemachinecannotbeconfiguredwithDNSclientherownTheDNSservicecannotberun

43.WhatarethebenefitsandscenariosofusingStubzones?

OneofthenewfeaturesintroducedintheWindowsServer2003basedimplementationofDNSarestubzones.Itsmainpurposeistoprovidenameresolutionindomains,forwhichalocalDNSserverisnotauthoritative.Thestubzonecontainsonlyafewrecords:

StartofAuthority(SOA)recordpointingtoaremoteDNSserverthatisconsideredtobethebestsourceofinformationaboutthetargetDNSdomain,oneormoreNameServer(NS)records(includingtheentryassociatedwiththeSOArecord),whichareauthoritativefortheDNSdomainrepresentedbythestubzone,correspondingArecordsforeachoftheNSentries(providingIPaddressesoftheservers).Whileyoucanalsoprovidenameresolutionforaremotedomainbyeithercreatingasecondaryzone(whichwasacommonapproachinWindowsServer2000DNSimplementation)ordelegation(whendealingwithacontiguousnamespace),suchapproachforcesperiodiczonetransfers,whicharenotneededwhenstubzonesareused.NecessitytotraversenetworkinordertoobtainindividualrecordshostedontheremoteNameServersismitigatedtosomeextentbycachingprocess,whichkeepsthemonthelocalserverforthedurationoftheirTimetoLive(TTL)parameter.Inaddition,recordsresidinginastubzoneareperiodicallyvalidatedandrefreshedinordertoavoidlamedelegations.

44.WhatarethebenefitsandscenariosofusingConditionalForwarding?

45.WhatarethedifferencesbetweenWindowsClustering,NetworkLoadBalancingandRoundRobin,andscenariosforeachuse?

Iwillmakeafewassumptionshere:

1)ByWindowsClusteringNetworkLoadBalancingyoumeanWindowsNetworkLoadBalancingsoftwareincludedinWindowsServersoftwarea.k.aNLB.,and2)ByRoundRobin,youmeanDNSRoundRobinmeaningtheabsenceofasoftwareorhardwareloadbalancingdevice,ortheconceptoftheRoundRobinalgorithmavailableinjustabouteveryloadbalancingsolution.



MicrosoftNLBisdesignedforasmallnumber(46)ofWindowsServersandalowtomoderatenumberofnewconnectionspersecond,toprovidedistributionofwebserverrequeststomultipleserversinavirtualresourcepool.Somewouldcallthisacluster,buttherearesuttledifferencesbetweenaclusteredgroupofdevicesandamorelooselyconfiguredvirtualpool.Fromthestandpointofscalabilityandperformance,almostallhardwareloadbalancingsolutionsaresuperiortothisandotherlessknownsoftwareloadbalancingsolutions[e.g.BrightTigercirca1998].

DNSRoundRobinisaninherentloadbalancingmethodbuiltintoDNS.WhenyouresolveanIPaddressthathasmorethanoneArecord,DNShandsoutdifferentresolutionstodifferentrequestinglocalDNSservers.Althoughthereareseveralfactorseffectingtheexactresultingalgorithm(e.g.DNScaching,TTL,multipleDNSservers[authoritativeorcached]),IstressthetermroughlywhenIsayitroughlyresultsinanevendistributionofresolutionstoeachoftheaddressesspecifiedforaparticularURL.Itdoesnothowever,consideravailability,performance,oranyothermetricandiscompletelystatic.ThebasicRRalgorithmisavailableinmanysoftwareandhardwareloadbalancingsolutionsandsimplyhandsthenextrequesttothenextresourceandstartsbackatthefirstresourcewhenithitsthelastone.

NLBisbasedonproprietarysoftware,meantforsmallgroupsofWindowsserversonlyonprivatenetworks,andisdynamicinnature(takesintoaccountavailabilityofaserver,andinsomecasesperformance).RoundRobin,DNSorotherwise,ismoregeneric,staticinnature(doesnottakeintoaccountanythingbuttheresourceisamemberoftheresourcepoolandeachmemberisequal),andrangesfromDNStothedefaultstaticloadbalancingmethodoneveryhardwaredeviceinthemarket.

46.HowdoIworkwiththeHostnamecacheonaclientcomputer?

47.HowdoIcleartheDNScacheontheDNSserver?Tocleartheservernamescache

*UsingtheWindowsinterface

*Usingacommandline

UsingtheWindowsinterface

1.OpenDNS.

2.Intheconsoletree,clicktheapplicableDNSserver.

Where?

*DNS/applicableDNSserver

3.OntheActionmenu,clickClearCache.

Notes

*Toperformthisprocedure,youmustbeamemberoftheAdministratorsgrouponthelocalcomputer,oryoumusthavebeendelegatedtheappropriateauthority.Ifthecomputerisjoinedtoadomain,membersoftheDomainAdminsgroupmightbeabletoperformthisprocedure.Asasecuritybestpractice,considerusingRunastoperformthisprocedure.



*ToopenDNS,clickStart,clickControlPanel,doubleclickAdministrativeTools,andthendoubleclickDNS.

Usingacommandline

1.OpenCommandPrompt.

2.TypethefollowingcommandandthenpressENTER:

DnscmdServerName/clearcache

48.Whatisthe224.0.1.24addressusedfor?

WINSservergroupaddress.UsedtosupportautodiscoveryanddynamicconfigurationofreplicationforWINSservers.Formoreinformation,seeWINSreplicationoverviewWINSservergroupaddress.UsedtosupportautodiscoveryanddynamicconfigurationofreplicationforWINSservers.

49.WhatisWINSandwhendoweuseit?

IntheWindowsServerfamily,theprimarymeansforclientcomputertolocateandcommunicatewithothercomputersonanInternetProtocol(IP)networkisbyusingDomainNameSystem(DNS).However,clientsthatuseolderversionsofWindows,suchasWindowsNT4.0,usenetworkbasicI/Osystem(NetBIOS)namesfornetworkcommunication.SomeapplicationsthatrunonWindowsServer2003mayalsouseNetBIOSnamesfornetworkcommunication.UsingNetBIOSnamesrequiresamethodofresolvingNetBIOSnamestoIP.UsingaWINSserverisessentialforanyWindowsclientcomputertoworkwithotherWindowscomputersovertheInternet.Inaddition,usingaWINSserverisessentialforanyWindowsclientcomputeratIndianaUniversitythatintendstouseMicrosoftnetworkresources.TouseWINSservices,youmustinsertintoyourTCP/IPnetworkingconfigurationtheIPaddressoftheWINSserversyouwishtouse.

50.CanyouhaveaMicrosoftbasednetworkwithoutanyWINSserveronit?WhataretheconsiderationsregardingnotusingWINS?

51.DescribethedifferencesbetweenWINSpushandpullreplications.

ToreplicatedatabaseentriesbetweenapairofWINSservers,youmustconfigureeachWINSserverasapullpartner,apushpartner,orbothwiththeotherWINSserver.

*ApushpartnerisaWINSserverthatsendsamessagetoitspullpartners,notifyingthemthatithasnewWINSdatabaseentries.WhenaWINSserverspullpartnerrespondstothemessagewithareplicationrequest,theWINSserversends(pushes)copiesofitsnewWINSdatabaseentries(alsoknownasreplicas)totherequestingpullpartner.*ApullpartnerisaWINSserverthatpullsWINSdatabaseentriesfromitspushpartnersbyrequestinganynewWINSdatabaseentriesthatthepushpartnershave.ThepullpartnerrequeststhenewWINSdatabaseentriesthathaveahigherversionnumberthanthelastentrythepullpartnerreceivedduringthemostrecentreplication.

52.WhatisthedifferencebetweentombstoningaWINSrecordandsimplydeletingit?

SimpledeletionremovestherecordsthatareselectedintheWINSconsoleonlyfromthelocalWINSserveryouarecurrentlymanaging.IftheWINSrecordsdeletedinthiswayexistinWINSdatareplicatedtootherWINSserversonyournetwork,theseadditionalrecordsarenotfullyremoved.



Also,recordsthataresimplydeletedononlyoneservercanreappearafterreplicationbetweentheWINSserverwheresimpledeletionwasusedandanyofitsreplicationpartners.Tombstoningmarkstheselectedrecordsastombstoned,thatis,markedlocallyasextinctandimmediatelyreleasedfromactiveusebythelocalWINSserver.Thismethodallowsthetombstonedrecordstoremainpresentintheserverdatabaseforpurposesofsubsequentreplicationoftheserecordstootherservers.Whenthetombstonedrecordsarereplicated,thetombstonestatusisupdatedandappliedbyotherWINSserversthatstorereplicatedcopiesoftheserecords.EachreplicatingWINSserverthenupdatesandtombstones

53.NametheNetBIOSnamesyoumightexpectfromaWindows2003DCthatisregisteredinWINS.

54.Describetheroleoftheroutingtableonahostandonarouter.

Duringtheprocessofrouting,decisionsofhostsandroutersareaidedbyadatabaseofroutesknownastheroutingtable.Theroutingtableisnotexclusivetoarouter.Dependingontheroutableprotocol,hostsmayalsohavearoutingtablethatmaybeusedtodecidethebestrouterforthepackettobeforwarded.HostbasedroutingtablesareoptionalfortheInternetProtocol,aswellasobsoleteroutableprotocolssuchasIPX.

55.Whatareroutingprotocols?Whydoweneedthem?Nameafew.

Aroutingprotocolisaprotocolthatspecifieshowrouterscommunicatewitheachother,disseminatinginformationthatenablesthemtoselectroutesbetweenanytwonodesonacomputernetwork,thechoiceoftheroutebeingdonebyroutingalgorithms.Eachrouterhasapriorknowledgeonlyofnetworksattachedtoitdirectly.Aroutingprotocolsharesthisinformationfirstamongimmediateneighbors,andthenthroughoutthenetwork.Thisway,routersgainknowledgeofthetopologyofthenetwork.Foradiscussionoftheconceptsbehindroutingprotocols,see:Routing.

ThetermroutingprotocolmayreferspecificallytooneoperatingatlayerthreeoftheOSImodel,whichsimilarlydisseminatestopologyinformationbetweenrouters.

ManyroutingprotocolsusedinthepublicInternetaredefinedindocumentscalledRFCs.[1][2][3][4]

Althoughtherearemanytypesofroutingprotocols,twomajorclassesareinwidespreaduseintheInternet:linkstateroutingprotocols,suchasOSPFandISIS;andpathvectorordistancevectorprotocols,suchasBGP,RIPandEIGRP.

56.Whatarerouterinterfaces?Whattypescantheybe?

Routerscanhavemanydifferenttypesofconnectors;fromEthernet,FastEthernet,andTokenRingtoSerialandISDNports.Someoftheavailableconfigurableitemsarelogicaladdresses(IP,IPX),mediatypes,bandwidth,andadministrativecommands.Interfacesareconfiguredininterfacemodewhichyougettofromglobalconfigurationmodeafterloggingin.ThemediatypeisEthernet,FastEthernet,GigabitEthernet,Serial,Tokenring,orothermediatypes.Youmustkeepinmindthata10MbEthernetinterfaceistheonlykindofEthernetinterfacecalledEthernet.A100MbEthernetinterfaceiscalledaFastEthernetinterfaceanda1000MbEthernetinterfaceiscalledaGigabitEthernetinterface.

57.InWindows2003routing,whataretheinterfacefilters?



58.WhatisNAT?

WindowsServer2003providesnetworkaddresstranslation(NAT)functionalityasapartoftheRoutingandRemoteAccessservice.NATenablescomputersonsmalltomediumsizedorganizationswithprivatenetworkstoaccessresourcesontheInternetorotherpublicnetwork.ThecomputersonaprivatenetworkareconfiguredwithreusableprivateInternetProtocolversion4(IPv4)addresses;thecomputersonapublicnetworkareconfiguredwithgloballyuniqueIPv4(or,rarelyatpresent,InternetProtocolversion6[IPv6])addresses.Atypicaldeploymentisasmallofficeorhomeoffice(SOHO),oramediumsizedbusinesss,thatusesRoutingandRemoteAccessNATtechnologytoenablecomputersontheinternalcorporatenetworktoconnecttoresourcesontheInternetwithouthavingtodeployaproxyserver.

59.WhatistherealdifferencebetweenNATandPAT?

TakeNAT(NetworkAddressTranslation)andPAT(PortAddressTranslation).NATallowsyoutotranslateormaponeIPaddressontoanothersingleipaddress.PATontheotherhandiswhatismostcommonlyreferredtoasNAT.InaPATsystemyouhaveasingleorgroupofpublicIPaddressesthataretranslatedtomultipleinternalipaddressesbymappingtheTCP/UDPportstodifferentports.Thismeansthatbyusingsomemagiconarouterorserveryoucangetaroundproblemsthatyoumighthavewithtwowebbrowserssendingarequestoutthesameport.

60.HowdoyouconfigureNATonWindows2003?

http://www.windowsnetworking.com/articles_tutorials/NAT_Windows_2003_Setup_Configuration.html

ConfigureRoutingandRemoteAccessToactivateRoutingandRemoteAccess,followthesesteps:

1.ClickStart,pointtoAllPrograms,pointtoAdministrativeTools,andthenclickRoutingandRemoteAccess.2.Rightclickyourserver,andthenclickConfigureandEnableRoutingandRemoteAccess.3.IntheRoutingandRemoteAccessSetupWizard,clickNext,clickNetworkaddresstranslation(NAT),andthenclickNext.4.ClickUsethispublicinterfacetoconnecttotheInternet,andthenclickthenetworkadapterthatisconnectedtotheInternet.Atthisstageyouhavetheoptiontoreducetheriskofunauthorizedaccesstoyournetwork.Todoso,clicktoselecttheEnablesecurityontheselectedinterfacebysettingupBasicFirewallcheckbox.5.ExaminetheselectedoptionsintheSummarybox,andthenclickFinish.

ConfiguredynamicIPaddressassignmentforprivatenetworkclientsYoucanconfigureyourNetworkAddressTranslationcomputertoactasaDynamicHostConfigurationProtocol(DHCP)serverforcomputersonyourinternalnetwork.Todoso,followthesesteps:

1.ClickStart,pointtoAllPrograms,pointtoAdministrativeTools,andthenclickRoutingandRemoteAccess.2.Expandyourservernode,andthenexpandIPRouting.3.RightclickNAT/BasicFirewall,andthenclickProperties.



4.IntheNAT/BasicFirewallPropertiesdialogbox,clicktheAddressAssignmenttab.5.ClicktoselecttheAutomaticallyassignIPaddressesbyusingtheDHCPallocatorcheckbox.Noticethatdefaultprivatenetwork192.168.0.0withthesubnetmaskof255.255.0.0isautomaticallyaddedintheIPaddressandtheMaskboxes.Youcankeepthedefaultvalues,oryoucanmodifythesevaluestosuityournetwork.6.IfyourinternalnetworkrequiresstaticIPassignmentforsomecomputerssuchasfordomaincontrollersorforDNSserversexcludethoseIPaddressesfromtheDHCPpool.Todothis,followthesesteps:1.ClickExclude.2.IntheExcludeReservedAddressesdialogbox,clickAdd,typetheIPaddress,andthenclickOK.3.Repeatstepbforalladdressesthatyouwanttoexclude.4.ClickOK.

ConfigurenameresolutionToconfigurenameresolution,followthesesteps:

1.ClickStart,pointtoAllPrograms,pointtoAdministrativeTools,andthenclickRoutingandRemoteAccess.2.RightclickNAT/BasicFirewall,andthenclickProperties.3.IntheNAT/BasicFirewallPropertiesdialogbox,clicktheNameResolutiontab.4.ClicktoselecttheClientsusingDomainNameSystem(DNS)checkbox.IfyouuseademanddialinterfacetoconnecttoanexternalDNSserver,clicktoselecttheConnecttothepublicnetworkwhenanameneedstoberesolvedcheckbox,andthenclicktheappropriatedialupinterfaceinthelist.

61.HowdoyouallowinboundtrafficforspecifichostsonWindows2003NAT?

YoucanusetheWindowsServer2003implementationofIPSectocompensateforthelimitedprotectionsprovidedbyapplicationsfornetworktraffic,orasanetworklayerfoundationofadefenseindepthstrategy.DonotuseIPSecasareplacementforotheruserandapplicationsecuritycontrols,becauseitcannotprotectagainstattacksfromwithinestablishedandtrustedcommunicationpaths.YourauthenticationstrategymustbewelldefinedandimplementedforthepotentialsecurityprovidedbyIPSectoberealized,becauseauthenticationverifiestheidentityandtrustofthecomputerattheotherendoftheconnection.

62.WhatisVPN?WhattypesofVPNdoesWindows2000andbeyondworkwithnatively?

VPNgivesextremelysecureconnectionsbetweenprivatenetworkslinkedthroughtheInternet.Itallowsremotecomputerstoactasthoughtheywereonthesamesecure,localnetwork.

L2TP(layer2tunnelingprotocol)

vpnserverisalsoknowasL2TPserverinnativemode&inPPTPinmixedmode



63.WhatisIAS?Inwhatscenariosdoweuseit?

IASiscalledasInternetAuthenticationService.ItsusedbyforconfiguringcentralisedauthenticationusingRADIUSserver.

64.WhatsthedifferencebetweenMixedmodeandNativemodeinADwhendealingwithRRAS?

WhenyouareinMixedmodecertainoptionsinthedialintaboftheuserproeprtiesaredisabled.AndsomeoftheRRASpoliciesarealsodisabled.SoifyouwanthighlevelsecuritywithalltheadvancedfeaturethenchangetheADtoNativemode.

65.WhatistheRASandIASgroupinAD?

Usedformanagingsecurityandallowingadministrationfortherespectiverolesoftheserver.

66.WhatareConditionsandProfileinRRASPolicies?

Theconditionsandprofilesareusedtosetsomerestrictionsbasedonthemediatype,connectionmethod,groupmembershipandlotmore.Soifusedmatchesthoseconditionsmentionedintheprofilethenhecanallowed/deniedaccesstoRAS/VPNserver.

67.WhattypesorauthenticationcanaWindows2003basedRRASworkwith?

ItsupportsauthenticationmethodslikeMSCHAPv2,MSCHAP,SPAP,EAP,Digestauthentication.(YoucancheckitbygoingtopropertiesofyourserverinRRAS)

68.HowdoesSSLwork?

Internetcommunicationtypicallyrunsthroughmultipleprogramlayersonaserverbeforegettingtotherequesteddatasuchasawebpageorcgiscripts.

Theouterlayeristhefirsttobehitbytherequest.ThisisthehighlevelprotocolssuchasHTTP(webserver),IMAP(mailserver),andFTP(filetransfer).

Determiningwhichouterlayerprotocolwillhandletherequestdependsonthetypeofrequestmadebytheclient.ThishighlevelprotocolthenprocessestherequestthroughtheSecureSocketsLayer.IftherequestisforanonsecureconnectionitpassesthroughtotheTCP/IPlayerandtheserverapplicationordata.

Iftheclientrequestedasecureconnectionthessllayerinitiatesahandshaketobeginthesecurecommunicationprocess.DependingontheSSLsetupontheserver,itmayrequirethatasecureconnectionbemadebeforeallowingcommunicationtopassthroughtotheTCP/IPlayerinwhichcaseanonsecurerequestwillsendbackanerroraskingforthemtoretrysecurely(orsimplydenythenonsecureconnection).

69.HowdoesIPSecwork?

IPSecisanInternetEngineeringTaskForce(IETF)standardsuiteofprotocolsthatprovidesdataauthentication,integrity,andconfidentialityasdataistransferredbetweencommunicationpointsacrossIPnetworks.IPSecprovidesdatasecurityattheIPpacketlevel.Apacketisadatabundlethatisorganizedfortransmissionacrossanetwork,anditincludesaheaderandpayload(thedatainthe



packet).IPSecemergedasaviablenetworksecuritystandardbecauseenterpriseswantedtoensurethatdatacouldbesecurelytransmittedovertheInternet.IPSecprotectsagainstpossiblesecurityexposuresbyprotectingdatawhileintransit.

70.HowdoIdeployIPSecforalargenumberofcomputers?

JustusethisprogramServerandDomainIsolationUsingIPsecandGroupPolicy

71.WhattypesofauthenticationcanIPSecuse?

DeployingL2TP/IPSecbasedRemoteAccess

DeployingL2TPbasedremoteaccessVPNconnectionsusingWindowsServer2003consistsofthefollowing:

*Deploycertificateinfrastructure

*DeployInternetinfrastructure

*DeployAAAinfrastructure

*DeployVPNservers

*Deployintranetinfrastructure

*DeployVPNclients

*Implantarcertificadoinfraestrutura*ImplantarinfraestruturaInternet*ImplantarinfraestruturaAAA*ImplementarVPNservidores*Implantarintranetinfraestrutura*ImplementarclientesVPN

72.WhatisPFS(PerfectForwardSecrecy)inIPSec?

Inanauthenticatedkeyagreementprotocolthatusespublickeycryptography,perfectforwardsecrecy(orPFS)isthepropertythatensuresthatasessionkeyderivedfromasetoflongtermpublicandprivatekeyswillnotbecompromisedifoneofthe(longterm)privatekeysiscompromisedinthefuture.Forwardsecrecyhasbeenusedasasynonymforperfectforwardsecrecy[1],sincethetermperfecthasbeencontroversialinthiscontext.However,atleastonereference[2]distinguishesperfectforwardsecrecyfromforwardsecrecywiththeadditionalpropertythatanagreedkeywillnotbecompromisedevenifagreedkeysderivedfromthesamelongtermkeyingmaterialinasubsequentrunarecompromised.

73.HowdoImonitorIPSec?

TotesttheIPSecpolicies,useIPSecMonitor.IPSecMonitor(Ipsecmon.exe)providesinformationaboutwhichIPSecpolicyisactiveandwhetherasecurechannelbetweencomputersisestablished.



74.LookingatIPSecencryptedtrafficwithasniffer.WhatpackettypesdoIsee?

Youcanseethepackagestopass,butyoucannotseeitscontents

IPSecPacketTypesIPSecpackettypesincludetheauthenticationheader(AH)fordataintegrityandtheencapsulatingsecuritypayload(ESP)fordataconfidentialityandintegrity.Theauthenticationheader(AH)protocolcreatesanenvelopethatprovidesintegrity,dataoriginidentificationandprotectionagainstreplayattacks.Itauthenticateseverypacketasadefenseagainstsessionstealingattacks.AlthoughtheIPheaderitselfisoutsidetheAHheader,AHalsoprovideslimitedverificationofitbynotallowingchangestotheIPheaderafterpacketcreation(notethatthisusuallyprecludestheuseofAHinNATenvironments,whichmodifypacketheadersatthepointofNAT).AHpacketsuseIPprotocol51.Theencapsulatingsecuritypayload(ESP)protocolprovidesthefeaturesofAH(exceptforIPheaderauthentication),plusencryption.ItcanalsobeusedinanullencryptionmodethatprovidestheAHprotectionagainstreplayattacksandothersuchattacks,withoutencryptionorIPheaderauthentication.ThiscanallowforachievingsomeofthebenefitsofIPSecinaNATenvironmentthatwouldnotordinarilyworkwellwithIPSec.ESPpacketsuseIPprotocol50.

75.WhatcanyoudowithNETSH?

Netshisacommandlinescriptingutilitythatallowsyouto,eitherlocallyorremotely,display,modifyorscriptthenetworkconfigurationofacomputerthatiscurrentlyrunning.

76.HowdoIlookattheopenportsonmymachine?

Windows:Openacommandprompt(Startbutton>Run>typecmd),andtype:netstata

Linux:OpenanSSHsessionandtype:netstatan

Comments(8)

8Comments

1. SyyedSahaballahTalaAppkiIlimmedindugnitaraqqiatafarmayayehnoteshumlogokeliyebahutmadadgarhaiAllahaapapnepiyaNabikesadkeaapkejayeztammanpurikareauraapkoharbalaaurtufansesalamtrakhe

CommentbyMohammedshamimJuly27,2011@4:11PM

ReplyJazakAllah!

CommentbyPinochio/zaibJuly28,2011@7:43AM

Reply2. SyyedSahaballahTalaAppkiilimmedindugnitaraqqiatafarmayayehnoteshumlogokeliyebahut

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CommentbyMohammedshamimJuly27,2011@4:13PM

Reply3. Assalam,

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Reply4. metounabletofind3/3link

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Reply5. []TechnicalInterviewQuestions(Part1/3)[Networking]Edited&MaintainedbySYEDJAHANZAIB

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CommentbymageshJune21,2014@12:29PM

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