10-11D1XQR《计算机网络》复习题及答案.doc 58页

'Chapter1ComputerNetworksandtheInternet1.The(A)isaworldwidecomputernetwork,thatis,anetworkthatinterconnectsmillionsofcomputingdevicesthroughouttheworld.A.publicInternetB.IntranetC.switchnetD.televisionnet2.Whichkindofmediaisnotaguidedmedia?(D)A.twisted-paircopperwireB.acoaxialcableC.fiberopticsD.digitalsatellitechannel3.Whichkindofmediaisaguidedmedia?(C)A.geostationarysatelliteB.low-altitudesatelliteC.fiberopticsD.wirelessLAN4.Theunitsofdataexchangedbyalink-layerprotocolarecalled(A).A.FramesB.SegmentsC.DatagramsD.bitstreams5.Whichofthefollowingoptionbelongstothecircuit-switchednetworks?(D)A.FDMB.TDMC.VCnetworksD.bothAandB6.(B)makessurethatneithersideofaconnectionoverwhelmstheothersidebysendingtoomanypacketstoofast.A.ReliabledatatransferB.FlowcontrolC.CongestioncontrolD.Handshakingprocedure7.(A)meansthattheswitchmustreceivetheentirepacketbeforeitcanbegintotransmitthefirstbitofthepacketontotheoutboundlink.A.Store-and-forwardtransmissionB.FDMC.End-to-endconnectionD.TDM8.Datagramnetworksandvirtual-circuitnetworksdifferinthat(C).A.datagramnetworksarecircuit-switchednetworks,andvirtual-circuitnetworksarepacket-switchednetworks. B.datagramnetworksarepacket-switchednetworks,andvirtual-circuitnetworksarecircuit-switchednetworks.C.datagramnetworksusedestinationaddressesandvirtual-circuitnetworksuseVC.numberstoforwardpacketstowardtheirdestination.D.datagramnetworksuseVC.numbersandvirtual-circuitnetworksusedestinationaddressestoforwardpacketstowardtheirdestination.9.Inthefollowingoptions,whichoneisnotaguidedmedia?(D)A.twisted-pairwireB.fiberopticsC.coaxialcableD.satellite10.Processingdelaydoesnotincludethetimeto(B).A.examinethepacket’sheaderB.waittotransmitthepacketontothelinkC.determinewheretodirectthepacketD.checkbit-errorinthepacket11.Inthefollowingfourdescriptions,whichoneiscorrect?(C)A.Thetrafficintensitymustbegreaterthan1.B.Thefractionoflostpacketsincreasesasthetrafficintensitydecreases.C.Ifthetrafficintensityisclosetozero,theaveragequeuingdelaywillbeclosetozero.D.Ifthetrafficintensityisclosetoone,theaveragequeuingdelaywillbeclosetoone.12.TheInternet’snetworklayerisresponsibleformovingnetwork-layerpacketsknownas(B)fromonehosttoanother.A.frameB.datagramC.segmentD.message13.Theprotocolsofvariouslayersarecalled(A).A.theprotocolstackB.TCP/IPC.ISPD.networkprotocol14.Therearetwoclassesofpacket-switchednetworks:(A)networksandvirtual-circuitnetworks.A.datagramB.circuit-switchedC.televisionD.telephone15.Accessnetworkscanbelooselyclassifiedintothreecategories:residentialaccess,companyaccessand(B)access.A.cabledB.wirelessC.campus D.cityareaQuestion16～17Suppose,aistheaveragerateatwhichpacketsarriveatthequeue,Risthetransmissionrate,andallpacketsconsistofLbits,thenthetrafficintensityis(16:B),anditshouldnogreaterthan(17:B).16.A.LR／a17.A.2B.La／RB.1C.Ra／LC.0D.LR／aD.118.IntheInternet,theequivalentconcepttoendsystemsis(A).A.hostsB.serversC.clientsD.routers19.IntheInternet,endsystemsareconnectedtogetherby(C).A.copperwireB.coaxialcableC.communicationlinksD.fiberoptics20.EndsystemsaccesstotheInternetthroughits(C).A.modemsB.protocolsC.ISPD.sockets21.Endsystems,packetswitches,andotherpiecesoftheInternet,run(D)thatcontrolthesendingandreceivingofinformationwithintheInternet.A.programsB.processesC.applicationsD.protocols22.Therearemanyprivatenetworks,suchasmanycorporateandgovernmentnetworks,whosehostscannotexchangemessageswithhostsoutsideoftheprivatenetwork.Theseprivatenetworksareoftenreferredtoas(C).A.internetsB.LANC.intranetsD.WAN23.Theinternetallows(D)runningonitsendsystemstoexchangedatawitheachother.A.clientsapplicationsB.serverapplicationsC.P2PapplicationsD.distributedapplications24.TheInternetprovidestwoservicestoitsdistributedapplications:aconnectionless unreliableserviceand(B)service.A.flowcontrolB.connection-orientedreliableC.congestioncontrolD.TCP25.Itdefinestheformatandtheorderofmessagesexchangedbetweentwoormorecommunicatingentities,aswellastheactionstakenonthetransmissionand/orreceiptofamessageorotherevent.Thesentencedescribes(B).A.InternetB.protocolC.intranetD.network26.Inthefollowingoptions,whichdoesnotdefineinprotocol?(D)A.theformatofmessagesexchangedbetweentwoormorecommunicatingentitiesB.theorderofmessagesexchangedbetweentwoormorecommunicatingentitiesC.theactionstakenonthetransmissionofamessageorothereventD.thetransmissionsignalsaredigitalsignalsoranalogsignals27.Inthefollowingoptions,whichisdefinedinprotocol?(A)A.theactionstakenonthetransmissionand/orreceiptofamessageorothereventB.theobjectsexchangedbetweencommunicatingentitiesC.thecontentintheexchangedmessagesD.thelocationofthehosts28.Inthefollowingoptions,whichdoesnotbelongtothenetworkedge?(B)A.endsystemsB.routersC.clientsD.servers29.Inthefollowingoptions,whichbelongstothenetworkcore?(B)A.endsystemsB.routersC.clientsD.servers30.Inthefollowingoptions,whichisnotthebundledwiththeInternet’sconnection-orientedservice?(B)A.reliabledatatransferB.guaranteeofthetransmissiontimeC.flowcontrolD.congestion-control31.Anapplicationcanrelyontheconnectiontodeliverallofitsdatawithouterrorandintheproperorder.Thesentencedescribes(C).A.flowcontrolB.congestion-controlC.reliabledatatransferD.connection-orientedservice 32.Itmakessurethatneithersideofaconnectionoverwhelmstheothersidebysendingtoomanypacketstoofast.Thesentencedescribes(A).A.flowcontrolB.congestion-controlC.connection-orientedserviceD.reliabledatatransfer33.IthelpspreventtheInternetfromenteringastateofgridlock.Whenapacketswitchbecomescongested,itsbufferscanoverflowandpacketlosscanoccur.Thesentencedescribes(B).A.flowcontrolB.congestion-controlC.connection-orientedserviceD.reliabledatatransfer34.TheInternet’sconnection-orientedservicehasaname,itis(A).A.TCPB.UDPC.TCP/IPD.IP35.Inthefollowingoptions,whichservicedoesnotbeprovidedtoanapplicationbyTCP?(C)A.reliabletransportB.flowcontrolC.videoconferencingD.congestioncontrol36.TheInternet’sconnectionlessserviceiscalled(B).A.TCPB.UDPC.TCP/IPD.IP37.Inthefollowingoptions,whichdoesnotuseTCP?(B)A.SMTPB.internettelephoneC.FTPD.HTTP38.Inthefollowingoptions,whichdoesnotuseUDP?(D)A.InternetphoneB.videoconferencingC.streamingmultimediaD.telnet39.Therearetwofundamentalapproachestobuildinganetworkcore,(B)andpacketswitching.A.electricalcurrentswitchingB.circuitswitchingC.dataswitching D.messageswitching40.In(C)networks,theresourcesneededalongapathtoprovideforcommunicationbetweentheendsystemarereservedforthedurationofthecommunicationsession.A.packet-switchedB.data-switchedC.circuit-switchedD.message-switched41.In(A)networks,theresourcesarenotreserved;asession’smessagesusetheresourcesondemand,andasaconsequence,mayhavetowaitforaccesstocommunicationlink.A.packet-switchedB.data-switchedC.circuit-switchedD.message-switched42.Inacircuit-switchednetwork,ifeachlinkhasncircuits,foreachlinkusedbytheend-to-endconnection,theconnectiongets(A)ofthelink’sbandwidthforthedurationoftheconnection.A.afraction1/nB.allC.1/2D.ntimes43.For(C),thetransmissionrateofacircuitisequaltotheframeratemultipliedbythenumberofbitsinaslot.A.CDMAB.packet-switchednetworkC.TDMD.FDM44.(B)meansthattheswitchmustreceivetheentirepacketbeforeitcanbegintotransmitthefirstbitofthepacketontotheoutboundlink.A.QueuingdelayB.Store-and-forwardtransmissionC.PacketlossD.Propagation45.Thenetworkthatforwardspacketsaccordingtohostdestinationaddressesiscalled(D)network.A.circuit-switchedB.packet-switchedC.virtual-circuitD.datagram46.Thenetworkthatforwardspacketsaccordingtovirtual-circuitnumbersiscalled(C)network.A.circuit-switchedB.packet-switchedC.virtual-circuitD.datagram 47.Inthefollowingentries,whichisnotakindofaccessnetwork?(D)A.residentialaccessB.companyaccessC.wirelessaccessD.localaccess48.Supposethereisexactlyonepacketswitchbetweenasendinghostandareceivinghost.ThetransmissionratesbetweenthesendinghostandtheswitchandbetweentheswitchandthereceivinghostareR1andR2,respectively.Assumingthattheswitchusesstore-and-forwardpacketswitching,whatisthetotalend-to-enddelaytosendapacketoflengthL?(Ignorequeuingdelay,propagationdelay,andprocessingdelay.)(A)A.L/R1＋L/R2B.L/R1C.L/R2D.noneoftheabove49.Thetimerequiredtoexaminethepacket’sheaderanddeterminewheretodirectthepacketispartofthe(B).A.queuingdelayB.processingdelayC.propagationdelayD.transmissiondelay50.Thetimerequiredtopropagatefromthebeginningofthelinktothenextrouteris(C).A.queuingdelayB.processingdelayC.propagationdelayD.transmissiondelay51.Considersendingapacketof3000bitsoverapathof5links.Eachlinktransmitsat1000bps.Queuingdelays,propagationdelayandprocessingdelayarenegligible.(6points)(1).Supposethenetworkisapacket-switchedvirtualcircuitnetwork.VCsetuptimeis0.1seconds.Supposethesendinglayersaddatotalof500bitsofheadertoeachpacket.Howlongdoesittaketosendthefilefromsourcetodestination?t=5*(3000+500)/1000+0.1=17.6s(2).Supposethenetworkisapacket-switcheddatagramnetworkandaconnectionlessserviceisused.Nowsupposeeachpackethas200bitsofheader.Howlongdoesittaketosendthefile?t=5*(3000+200)/1000=16s(3).Supposethatthenetworkisacircuit-switchednetwork.Furthersupposethatthetransmissionrateofthecircuitbetweensourceanddestinationis200bps.Assuming0.02ssetuptimeand200bitsofheaderappendedtothepacket,howlongdoesittaketosendthepacket?t=(3000+200)/200+0.02=16.02s Chapter2ApplicationLayer1.Inthefollowingfourdescriptions,whichoneiscorrect?A.InC/Sarchitecture,clientscommunicatewitheachotherdirectly.B.InC/Sarchitecture,clienthasafixedwell-knownaddress.C.InP2Parchitecture,peerscommunicatewitheachotherdirectly.D.InP2Parchitecture,peerhasafixedwell-knownaddress.2.Inthecontextofacommunicationsessionbetweenapairofprocess,theprocessthatinitiatesthecommunicationislabeledasthe,theprocessthatwaitstobecontactedtobeginthesessionislabeledasthe.A.clientprocess,serverprocessB.sendingprocess,receivingprocessC.inputprocess,outputprocessD.communicatingprocess,connectingprocess3.Asocketistheinterfacebetweenwithinahost.A.thenetworklayerandthelinklayerB.thelinklayerandthephysicallayerC.theapplicationlayerandthetransportlayerD.thetransportlayerandthenetworklayer4.Inthefollowingapplications,whichoneisaloss-tolerantapplication?A.E-mailB.filetransferC.instantmessagingD.real-timeaudio5.Inthefollowingapplications,whichoneisabandwidth-sensitiveapplication?A.E-mailB.webapplicationC.real-timeaudioD.filetransfer6.TheserviceofTCPcan’tguarantee.A.deliveryofalldatawithouterrorB.deliveryofalldataintheproperorderC.therateofdeliveryD.congestioncontrol7.Inthefollowingapplications,whichoneusesUDP?A.E-mailB.webapplicationC.filetransferD.DNS8.InthefollowingdescriptionsaboutHTTP,whichoneisnotcorrect?A.HTTPusesnon-persistentconnectionsinitsdefaultmode.B.HTTPusesTCPasitsunderlyingtransportprotocol.C.HTTPisastatelessprotocol.D.HTTPisclient-serverarchitecture.9.SupposeawebpageconsistsofabaseHTMLfile,5JEPGimagesandajavaapplet,andalsosupposeHTTPusespersistentconnectionwithoutpipelining,thetotalresponsetimeis.A.2RTTB.8RTTC.12RTTD.14RTT10.InHTTPresponsemessage,iftherequestedHTTPprotocolversionisnotsupported,thestatuscodeis.A.200B.301C.400D.50511.Theportnumberofwebapplicationis.A.25B.20C.80D.5312.AnetworkentitythatsatisfiesHTTPrequestsonthebehalfofanoriginwebserveris.A.serverfarmB.serverstackC.proxyserverD.edgeserver 13.Inthefollowingdescriptionsaboutpersistentconnection,whichoneisnotcorrect?A.TheserverleavestheTCPconnectionopenaftersendingaresponse.B.EachTCPconnectionisclosedaftertheserversendingoneobject.C.Therearetwoversionsofpersistentconnection:withoutpipeliningandwithpipelining.D.ThedefaultmodeofHTTPusespersistentconnectionwithpipelining.14.FTPusestwoparallelTCPconnectionstotransferafile,thereare.A.controlconnectionanddataconnectionB.receivingconnectionandsendingconnectionC.clientconnectionandseverconnectionD.programconnectionandprocessconnection15.InthefollowingdescriptionsaboutFTP,whichoneiscorrect?A.FTPisp2parchitecture.B.FTPsendsitscontrolinformationout-of-band.C.FTPusespersistentconnection.D.FTPisastatelessprotocol.16.InthecommandsofFTP,whichonedoesnothaveparameter?A.USERB.PASSC.LISTD.STOR17.TheInternetmailsystemhasthreecomponentswhichtheyare.A.useragent,SMTP,POP3B.SMTP,POP3,IMAPC.useragent,SMTP,IMAPD.useragent,SMTP,mailserver18.IfthestatuscodeinHTTPresponsemessageis404,itmeans.A.Requestsucceeded.B.Therequesteddocumentdoesn’texitonthisserver.C.Thisisagenericerrorcodeindicatingthattherequestcouldnotbeunderstoodbytheserver.D.Requestedobjecthasbeenpermanentlymover.19.ComparisonHTTPwithSMTP,thecorrectis.A.HTTPisapushprotocol,andSMTPisapullprotocol.B.Inthedefaultmode,bothofthemusepersistentconnection.C.HTTPplacesallofthemessage’sobjectsintoonemessage,andSMTPsendseveryobjectonebyone.D.HTTPrequireseachmessagetobein7-bitASCIIformat,andSMTPdoesn’timposethisrestriction.20.TheheadersintheMIMEmessagemustincludeexcept.A.FromB.Content-typeC.Content-transfer-encodingD.MIMEversion21.Inthefollowingprotocol,whichoneisstateless?A.POP3B.SMTPC.FTPD.IMAP22.DNSmeans.A.DataNameSystemB.DataNationalSystemC.DomainNameSystemD.DomainNationalSystem23.TherearethreeclassesofDNSserverexcept.A.RootDNSserverB.LocalDNSserverC.TLDserverD.AuthoritativeDNSserver24.DNSprovidessomeservicesexcept.A.HostaliasingB.MailserveraliasingC.LoaddistributionD.Asinglepointoffailure 25.TherearethreearchitecturesforlocatingcontentinP2Pfilesharing,KaZaAuses.A.CentralizedDirectoryB.QueryFloodingC.ExploitingHeterogeneityD.IncentivePriorities26.TherearethreearchitecturesforlocatingcontentinP2Pfilesharing,Napsteruses.A.CentralizedDirectoryB.QueryFloodingC.ExploitingHeterogeneityD.IncentivePriorities27.ThefollowingarchitecturesinP2Pfilesharing,whichisanoverlaynetwork?A.CentralizedDirectoryB.QueryFloodingC.ExploitingHeterogeneityD.IncentivePriorities28.Thetimeittakesforasmallpackettotravelfromclienttoserverandthenbacktotheclientis.A.round-traveltimeB.next-hoptimeC.round-triptimeD.prefix-matchingtime29.SupposeA(withaWeb-basede-mailaccount)sendsamessagetoB(whoaccesseshismailserverusingPOP3),whichapplication-layerprotocolisnotused?A.HTTPB.SMTPC.POP3D.IMAP30.Inthefourfollowingoptions,whichprotocolisincludedinMailAccessProtocol?A.SMTPB.DHCPC.IMAPD.FTP31.InFTPcommands,isusedtosenduserpasswordtotheserver.A.UserB.PassC.RetrD.Stor32.ThefunctionoftheadditionalheaderfieldinMIMEContent-Typeis.A.toconvertthemessagebodytoitsoriginnon-ASCIIformB.todeterminewhatactionsitshouldtakeonmessagebodyC.tosendanE-mailtothereceivinguseragentD.toindicatewhattypethemessageis33.Inthefourfollowingoptions,whichapplicationisorganizedashybridofC/SandP2Parchitecture?A.E-mailB.OICQC.FiletransferD.Webapplication34.Inthefourfollowingoptions,whichisnotacentralizedDNSdesign’sproblem?A.asinglepointoffailureB.trafficvolumeC.distantcentralizeddatabaseD.slow35.Inthefollowingoptions,fromtheapplicationdeveloper’sperspective,whichisnotcorrect?A.thenetworkarchitectureisfixedB.thenetworkarchitectureprovidesaspecificsetofservicestoapplicationsC.theapplicationarchitectureisdesignedbythephysicaldevicesD.theapplicationarchitecturedictateshowtheapplicationisorganizedoverthevariousendsystems36.Therearethreepredominantarchitecturesusedinmodernnetworkapplications,whichoneisnotincluded?A.theclient-serverarchitectureB.theP2ParchitectureC.ahybridoftheclient-serverandP2ParchitectureD.ahybridoftheclient-serverandbrowser-serverarchitecture37.InthefollowingoptionsaboutC/Sarchitecture,whichisnotcorrect? A.InC/Sarchitecture,thereisanalways-onhost,calledtheserver.B.InC/Sarchitecture,thereisanalways-onhost,calledtheclient.C.Theserverhasafixed,well-knownaddress,calledIPaddress.D.Clientsdonotdirectlycommunicatewitheachother.38.areoftenusedtocreateapowerfulvirtualserverinC/Sarchitecture.A.PeersB.ServerfarmC.serverstackD.localserver39.Aprocesssendsmessagesinto,andreceivesmessagesfrom,thenetworkthroughits.A.socketB.programC.clientD.peer40.Whichoneisnotdefinedbyanapplication-layerprotocol?A.thetypesofmessagesexchangedB.thesyntaxofvariousmessagetypesC.thesemanticsofthefieldsD.rulesfordeterminingwhenandhowtotranslatethesocket41.HTTPcanusetwotypesofconnections,whichare.A.persistentandnon-persistentconnectionB.connectionwithpipeliningandwithoutpipeliningC.TCPandUDPD.parallelandserialconnection42.takesforasmallpackettotravelfromclienttoserverandthenbacktotheclient.A.RDTB.thresholdC.RTTD.overhead43.ThedefaultmodeofHTTPuses.A.non-persistentconnectionwithpipeliningB.non-persistentconnectionwithoutpipeliningC.persistentconnectionwithpipeliningD.persistentconnectionwithoutpipelining44.InHTTPrequestmessages,therequestlinehasthreefields,thereare.A.themethodfield,theURLfieldandtheHTTPversionfieldB.themethod,theconnectionandURLfieldC.theuser-agent,themethodandHTTPversionfieldD.theuser-agent,theURLandtheHTTPversionfield45.IntheheaderlinesofHTTPrequestmessage,ifthefieldofConnectionisclose,itspecifies.A.thehostonwhichobjectresidesB.whattypeoftheuseragentC.thatthebrowserwantstheservertoclosetheconnectionaftersendingtherequestedobjectD.whichlanguagecanthebrowserreceive46.InHTTPresponsemessage,ifthestatuscodeis404,itmeans.A.requestsucceededandtheinformationisreturnedintheresponseB.requestedobjecthasbeenpermanentlymovedC.therequestedHTTPprotocolversionisnotsupportedbytheserverD.therequesteddocumentdoesnotexistonthisserver47.isanetworkentitythatsatisfiesHTTPrequestsonthebehalfofanoriginWebserver. A.proxyserverB.localserverC.DNSserverD.Webserver48.Inthefollowingfouroptionsaboutwebcache,whichoneisnotcorrect?A.Awebcacheisbothaserverandaclientatthesametime.B.AwebcacheispurchasedandinstalledbyanISP.C.Awebcachecanraisetheresponsetimeforaclientrequest.D.Awebcachecanreducetrafficonaninstitution’saccesslinktotheInternet.49.TherequestmessageintheconditionalGETmustincludetheheaderline.A.Last-ModifiedB.Last-ReferencedC.If-Modified-SinceD.If–Referenced-Since50.FTPusestwoparallelconnectionstotransferafile,theyare.A.TCPandUDPconnectionB.connectionwithpipeliningandwithoutpipeliningC.controlandataconnectionD.client-serverandbrowser-serverconnection51.InFTPcommands,whichoneisusedtoasktheservertosendbackalistofallfilesinthecurrentremotedirectory?A.USERB.PASSC.LISTD.RETR52.IntheInternetmailsystem,allowuserstoread,replyto,forward,saveandcomposemessage.A.UseragentsB.mailserversC.SMTPD.TCP53.ThetwokeyMIMEheadersforsupportingmultimediaare.A.Content-TypeandMIME-VersionB.Content-TypeandContent-Transfer-EncodingC.Content-Transfer-EncodingandMIME-VersionD.MIME-VersionandMIME-Type54.ForInternetmail,themailaccessprotocolisusedto.A.transfermailfromtherecipient’smailservertotherecipient’suseragentB.transfermailfromthesender’smailservertotherecipient’smailserverC.translatethemailfromthesender’smailserverD.translatethemailintotherecipient’smailserver55.POP3progressesthroughthreephases,whichtheyare.A.authorization,translationandtransactionB.authorization,translationandupdateC.authorization,transactionandupdateD.translation,transactionandupdate56.Inthefollowingfourservices,whichonecannotprovidebyDNS?A.HostaliasingB.MailserveraliasingC.translatehostnametoIPaddressesD.translateMACaddressestoIPaddresses57.TherearethreeclassesofDNSservers,thereare.A.rootDNSserver,top-leveldomainDNSserverandlocalDNSserverB.rootDNSserver,top-leveldomainDNSserverandauthoritativeDNSserverC.rootDNSserver,localDNSserverandauthoritativeDNSserverD.rootDNSserver,localDNSserverandtop-leveldomainDNSserver 58.InthefollowingfouroptionsaboutPOP3,whichoneisnotcorrect?A.Theuseragentemployedonlythreecommands:List,RetrandQuitB.TheserverdoesnotcarrystateinformationacrossPOP3sessionsC.Theportnumberis110D.ThePOP3protocoldoesnotprovideanymeansforausertocreateremotefoldersandassignmessagestofolders.59.AresourcerecordinDNSdistributeddatabaseisafour-tuple,whichfieldcanbeignored?A.NameB.ValueC.TypeD.TTL60.InthefollowingfouroptionsaboutDNSresourcerecord,whichoneiscorrect?A.ThemeaningofNameandValuedependonType.B.ThemeaningofValueandTypedependonName.C.IfType=A,thenNameisadomainandValueistheIPaddressforthehostname.D.IfType=MX,thenNameisdomainandValueistheIPaddressforthehostname.61.InthefollowingfouroptionsaboutDNSmessages,whichoneisnotcorrect?A.ThereareonlytwokindsofDNSmessage.B.Bothqueryandreplymessagehavethesameformat.C.TheheadersectioninDNSmessagehas12bytes.D.Theauthoritysectioncontainstheresourcerecordsforthesamethatwasoriginallyqueried.62.InDNSmessage,containsinformationaboutthequerythatisbeingmade.A.authoritysectionB.questionsectionC.answersectionD.additionalsection63.TherearethreetechniquesareemployedinmostanyP2Pfile-sharingsystems,whichoneisnotinclude?A.RequestqueuingB.incentiveprioritiesC.paralleldownloadingD.Responsequeuing64.InthefollowingfouroptionsaboutP2Pfile-sharing,whichoneisnotcorrect?A.P2Pfile-sharingishighlyscalable.B.P2Pfile-sharingreliesonP2Parchitecture.C.ThemeansforlocatingcontentindifferentP2Pfile-sharingaredifferent.D.P2Pfile-sharingsystemsnotonlyshareMP3s,butalsovideos,software,documentsandimages.65.InMIMEheaderlines,specifiesthenameoftheSMTPserverthatsentthemessage(from),thenameoftheSMTPserverthatreceivedthemessage(by),andthetimeanwhichthereceivingserverreceivedthemessage.A.ReceivedB.FromC.ToD.MIME-Version66.IftheheaderlineConnectionisclose,itmeansthattheclientwants.A.persistentconnectionwithpipeliningB.persistentconnectionwithoutpipeliningC.nonpersistentconnectionD.notconnection67.InHTTPrequestmessage,theentitybodyisemptywiththemethod,butisusedwiththemethod.A.GET,POSTB.POST,GETC.GET,HEADD.POST,HEAD 68.InHTTPresponsemessage,iftheDate:header;oneindicatesthetimeFri.08Aug.200812:00:00GMT,theLast-Modified:headerlinecannotbe.A.Fri.08Aug.200811:00:00GMTB.Fri.08Aug.200811:30:00GMTC.Fri.08Aug.200812:00:00GMTD.Fri.08Aug.200812:30:00GMT69.Inthefollowingfouroptions,whichoneisnotthepartofcookietechnology?A.CookieheaderlinesintheHTTPresponsemessageandrequestmessage.B.Onecookieheaderfilekeptontheuser’sendsystemandmanagedbytheuser’sbrowser.C.AnetworkentitythatsatisfiesHTTPrequestsonthebehalfofanoriginWebserver.D.Aback-enddatabaseattheWebsite70.On-topofstatelessHTTP,canbeusedtocreateausersessionlayer.A.proxyserverB.WebcacheC.cookieD.socket71.Processescommunicatewitheachotherbyreadingfromandwritingto.A.programsB.threadsC.socketsD.channels72.Inthefollowingfouroptionsaboutnetworkarchitecture,whichoneisnotcorrect?A.Thenetworkarchitectureisfixed.B.Thenetworkarchitectureprovidesaspecificsetofservicestoapplication.C.Thenetworkarchitectureisdesignedbyapplicationdeveloper.D.Thenetworkarchitecturedictateshowtheapplicationisorganizedoverspecialserver.73.InClient-Serverarchitecture,theclientsvisittheserver’sthrough.A.client’ssocketB.client’sIPaddressC.server’ssocketD.server’sIPaddress74.canbethoughtofasaprogramthatisrunningwithinendsystem.A.processB.threadC.socketD.context75.APImeans.A.ApplicationProgramInterfaceB.ApplicationProcessInterfaceC.AppellationProgramInterfaceD.AppellationProcessInterface76.Onehostcanberunningmanynetworkapplications,sothesystemassignsthemdifferenttodistinguisheachother.A.IPaddressB.portnumberC.hostnameD.section77.Inthefollowingfourapplications,whichoneisbothbandwith-sensitiveandrequiretighttimingconstraints?A.real-timeaudioB.filetransferC.E-mailD.Webdocuments78.TheportnumberoftheWebserveris.A.25B.20C.80D.808079.Theportnumberofthemailserveris.A.25B.20C.80D.808080.LooktheURLhttp://www.djtu.edu.cn/rjxy/index.html,theobject’spathnameis.A.www.djtu.edu.cnB.www.djtu.edu.cn/rjxyC./rjxy/index.htmlD.index.html81.EachURLhascomponents,theyare.A.transportprotocolandobject’spathnameB.hostnameandobject’spathname C.transportprotocolandhostnameD.clientnameandservername1.ConsideranHTTPclientwillrequestaWEBpagefromaWEBserver.SupposetheURLofthepageiswww.stdjtu.edu.cn/somedepartment/somedir/exp.html.TheclientdoesnotwanttousepersistentconnectionsandwanttoreceiveFrenchversionoftheobject.TheuseragentisWindowsNT5.1.Givetherequestmessageaccordingtothegivenformat.Solution:Requestline:GET/somedepartment/somedir/exp.htmlHTTP/1.1(orHTTP/1.0)Headerlines:Host:www.stdjtu.edu.cn(stdjtu.edu.cn)Connection:closeUser-agent:windowsNT5.1(orwindowsNT/5.1)Accept-language:fr(orFrench)2.TelnetintoaWebserverandsendamultilinerequestmessage.IncludeintherequestmessagetheIf-modified-since:headerlinetoforcearesponsemessagewiththe304NotModifiedstatuscode.Solution:Requestline:GET/somedir/exp.htmlHTTP/1.1Headerlines:Host:www.djtu.edu.cnConnection:closeUser-agent:windowsNT5.1If-Modified-Since:Thu,30May200712:00:00GMTAccept-language:fr3.SupposewithinyouWebbrowseryouclickonalinktoobtainaWebpage.TheIPaddressfortheassociatedURLisnotcachedinyourlocalhost,soaDNSlook-upisnecessarytoobtaintheIPaddress.SupposethatnDNSserversarevisitedbeforeyourhostreceivestheIPaddressfromDNS;thesuccessivevisitsincuranRTTofRTT1,…，RTTn.FurthersupposethattheWebpageassociatedwiththelinkcontainsexactlyoneobject,consistingofasmallHTMLtext.LetRTT0denotetheRTTbetweenthelocalhostandtheservercontainingtheobject.Assumingzerotransmissiontimeoftheobject,howmuchtimeelapsesfromwhentheclientclicksonthelinkuntiltheclientreceivestheobject?2RTT0+RTT1+RTT2+....+RTTn4.Consideraccessingyoure-mailwithPOP3.a.SupposeyouhaveconfiguredyourPOPmailclienttooperateinthedownload-anddeletemode.Completethefollowingtransaction:C:listS:1498C:2912S:.C:retr1S:blahblah……S:……blahS:.C:dele1 C:retr2S:blahblah……S:……blahS:.C:dele2C:quitb.SupposeyouhaveconfiguredyourPOPmailclienttooperateinthedownload-and-keepmode.Completethefollowingtransaction:C:listS:1498C:2912S:.C:retr1S:blahblah……S:……blahS:.C:retr2S:blahblah……S:……blahS:.C:quit5.Supposethatyousendane-mailmessagewhoseonlydataisamicrosoftexcellattachment.Whatmighttheheaderlines(includingMIMElines)looklike?From:123@xxx.comTo:456@yyy.comSubject:zzzzzzzMIME-version:1.0content-transfer-encoding:base64content-type:application/Msexcel Chapter3TransportLayer1.Atransport-layerprotocolprovidesforlogicalcommunicationbetween____.A.ApplicationprocessesB.HostsC.RoutersD.Endsystems2.Transport-layerprotocolsrunin____.A.ServersB.ClientsC.RoutersD.Endsystems3.Intransportlayer,thesendsidebreaksapplicationmessagesinto____,passestonetworklayer.A.FramesB.SegmentsC.Data-gramsD.bitstreams4.Servicesprovidedbytransportlayerinclude____.A.HTTPandFTPB.TCPandIPC.TCPandUDPD.SMTP5.WhichofthefollowingservicesisnotprovidedbyTCP?A.DelayguaranteesandbandwidthguaranteesB.ReliabledatatransfersandflowcontrolsC.CongestioncontrolsD.In-orderdatatransfers6.Thesetwominimaltransport-layerservices----____and____----aretheonlytwoservicesthatUDPprovides!A.process-to-processdatadelivery,errorcheckingB.congestioncontrol,reliabledatatransferC.flowcontrol,congestioncontrolD.In-orderdatatransfer,errorchecking7.Portnumber’sscopeis____to____.A.0,1023B.0,65535C.0,127D.0,2558.Theportnumbersrangingfrom____to____arecalledwell-knownportnumberandarerestricted.A.0,1023B.0,65535 C.0,127D.0,2559.UDPsocketidentifiedbytwocomponents,theyare____.A.sourceIPaddressesandsourceportnumbersB.sourceIPaddressesanddestinationIPaddressesC.destinationIPaddressanddestinationportnumbersD.destinationportnumbersandsourceportnumbers10.TCPsocketidentifiedbya(an)____.A.1-tupleB.2-tupleC.3-tupleD.4-tuple11.WhichofthefollowingapplicationsnormallyusesUDPservices?A.SMTPB.StreamingmultimediaC.FTPD.HTTP12.Reliabledatatransferprotocoloveraperfectlyreliablechannelis____.A.rdt1.0B.rdt2.0C.rdt3.0D.rdt2.113.Reliabledatatransferprotocoloverachannelwithbiterrorsandpacketlossesis____.A.rdt1.0B.rdt2.0C.rdt3.0D.rdt2.114.Whichofthefollowingaboutreliabledatatransferoverachannelwithbiterrorsisnotcorrect?A.RDT2.0:assumingACKandNAKwillnotbecorruptedB.RDT2.1:assumingACKandNAKcanbecorruptedC.RDT2.2:onlyuseACK-sD.RDT2.2:usebothACK-sandNAK-s15.Whichofthefollowingprotocolsisnotpipeliningprotocols?A.TCPB.rdt3.0C.GO-BACK-ND.selectiverepeat16.WhichofthefollowingisnotcorrectaboutGBNprotocol?A.OnlyusingACK-sB.UsingcumulativeACK-sC.Receiverdiscardsallout-of-orderpacketsD.Itisnotpipelinedprotocol17.WhichofthefollowingisnotcorrectaboutSRprotocol? A.receiverindividuallyacknowledgesallcorrectlyreceivedpacketsB.senderonlyresendspacketsforwhichACKnotreceivedC.Itlimitssequencenumberofsentbutun-ACK-edpacketsD.Itisnotapipelinedprotocol18.WhichofthefollowingaboutTCPconnectionisnotcorrect?A.ItisabroadcastconnectionB.Itisapoint-to-pointconnectionC.ItisapipelinedconnectionD.Itisafullduplexconnection19.TheSYNsegmentisusedfor____.A.TCPconnectionsetupB.TCPflowcontrolC.TCPcongestioncontrolD.ClosingaTCPconnection20.TheFINsegmentisusedfor____.A.TCPconnectionsetupB.TCPflowcontrolC.TCPcongestioncontrolD.ClosingaTCPconnection21.HowdoesTCPsenderperceivecongestion?A.ThroughatimeouteventB.ThroughareceivingduplicateACK-seventC.BothAandBD.EitherAorB22.Extendinghost-to-hostdeliverytoprocess-to-processdeliveryiscalledtransport-layer____and.A.multiplexingandde-multiplexingB.storingandforwardingC.forwardingandfilteringD.switchingandrouting23.UDPisa____servicewhileTCPisaconnection-orientedservice.A.ConnectionlessB.ReliableC.Connection-orientedD.In-order24.TheUDPheaderhasonlyfourfields,theyare____.A.Sourceportnumber,destinationportnumber,lengthandchecksumB.Sourceportnumber,destinationportnumber,sourceIPanddestinationIPC.sourceIP,destinationIP,sourceMACaddressanddestinationMACaddressD.sourceIP,destinationIP,sequencenumberandACKsequencenumber25.Therearetwo16-bitintegers:1110011001100110,1101010101010101.Theirchecksumis____.A.0100010001000011B.1011101110111100 C.1111111111111111D.100000000000000026.Themaximumamountofdatathatcanbegrabbedandplacedinasegmentislimitedbythe____.A.Maximumsegmentsize(MSS)B.MTUC.ChecksumD.Sequencenumber27.TheMSSistypicallysetbyfirstdeterminingthelengthofthelargestlink-layerframethatcanbesentbythelocalsendinghost----theso-called____.A.Maximumtransmissionunit(MTU)B.MSSC.ChecksumD.Sequencenumber28.AFilesizeof500,000bytes,MSSequals1000bytes.WhenwewanttotransmitthisfilewithTCP,thesequencenumberofthefirstsegmentis0,andthesequencenumberofthesecondsegmentis____.A.000B.999C.1001D.50000029.BecauseTCPonlyacknowledgesbytesuptothefirstmissingbyteinthestream,TCPissaidtoprovide____.A.CumulativeacknowledgementsB.SelectiveacknowledgementsC.3duplicateACKsD.positiveACKs30.Providedα=0.125,currentvalueofEstimated-RTTis0.4s,Sample-RTTis0.8s,thenthenewvalueofEstimated-RTTis____s.A.0.45B.0.6C.0.7D.0.831.ProvidedRcvBuffer=20,LastByteRcvd=20,LastByteRead=15,thenRcvWindow=____.A.14B.15C.16D.1032.TCPservicedoesnotprovide____.A.ReliabledatatransferB.FlowcontrolC.DelayguaranteeD.Congestioncontrol33.TherearetwostatesinTCPcongestioncontrol,whichare____.A.slowstartandcongestionavoidanceB.safestartandcongestionavoidance C.slowstartandcongestionabandonD.safestartandcongestionabandon34.Thetransport-layerprotocolprovideslogicalcommunicationbetween____,andthenetwork-layerprotocolprovideslogicalcommunication____.A.hosts,processesB.processes,hostsC.threads,processesD.processes,threads35.ToimplementthemulticastservicestheInternetemploysthe____protocol.A.FTPB.TCPC.IGMPD.UDP36.Ifanapplicationdeveloperchooses____protocol,thentheapplicationprocessisalmostdirectlytalkingwithIP.A.HTTPB.RIPC.CSMA/CDD.UDP37.____maintainsconnection-stateintheendsystems.Thisconnectionstateincludesreceiveandsendbuffers,congestion-controlparameters,andsequenceandacknowledgmentnumberparameters.A.UDPB.TCPC.DNSD.HTTP38.ThehostthatinitiatesthesessionintheInternetislabeledas____.A.serverB.useragentC.clientD.router39.WithTCPthereisno_____betweensendingandreceivingtransport-layerentities.A.flowcontrolB.handshakingC.congestioncontrolD.VCsetup40.TheInternet’s____servicehelpspreventtheInternetfromenteringastateofgridlock.A.datagramB.congestioncontrolC.slidingwindowD.timeoutevent41.Connectionsetupatthetransportlayerinvolves____.A.serverB.onlythetwoendsystemsC.clientD.router42.A____layerprotocolprovidesforlogicalcommunicationbetweenapplications.A.transportB.applicationC.networkingD.MAC43.Instaticcongestionwindow,ifitsatisfiesW*S/R>RTT+S/R,theLatencyis____.A.W*S/R–(RTT+S/R)B.2RTT+O/RC.2RTT+O/R+(k-1)[W*S/R-(RTT+S/R)]D.2RTT+S/R44.Thereceivesideoftransportlayerreassemblessegmentsintomessages,passesto____layer.A.Application B.NetworkingC.PhysicalD.MAC45.Inthefollowingfouroptions,whichoneiscorrect?A.ThevariationsintheSampleRTTaresmoothedoutinthecomputationoftheEstimatedRTTB.Thetimeoutshouldbelessthantheconnection’sRTTC.SupposethatthelastSampleRTTinaTCPconnectionisequalto1sec.ThenthecurrentvalueofTimeoutIntervalwillnecessarilybe≥1secD.SupposethatthelastSampleRTTinaTCPconnectionisequalto1sec.ThenthecurrentvalueofTimeoutIntervalwillnecessarilybe≤1sec46.TheportnumberusedbyHTTPis____.A.80B.25C.110D.5347.TheportnumberusedbySMTPis____.A.80B.25C.110D.5348.Theportnumberusedbypop3is____.A.80B.25C.110D.5349.TheportnumberusedbyDNSis____.A.80B.25C.110D.5350.TheportnumberusedbyFTPis____.A.20and21B.20C.21D.5351.AUDPsocketidentifiedbya____tuple(s).A.2B.4C.1D.352.ATCPsocketidentifiedbya____tuple(s).A.2B.4 C.1D.353.ATCPsocketdoesnotinclude____.A.SourceMACaddressB.SourceportnumberC.DestinationIPaddressD.Destinationportnumber54.WhichoffollowingaboutUDPisnotcorrect.A.ItisareliabledatatransferprotocolB.ItisconnectionlessC.nohandshakingbetweenUDPsender,receiverD.itisabesteffortserviceprotocol55.DNSuses____service.A.TCPB.UDPC.BothTCPandUDPD.Noneofabove56.WhichoffollowingaboutUDPiscorrect?A.Finerapplication-levelcontroloverwhatdataissent,andwhenB.Noconnectionestablishment(whichcanadddelay),sonodelayforestablishaconnectionC.Noconnectionstate(so,UDPcantypicallysupportmanyactiveclients)D.Largepacketheaderoverhead(16-B)57.Streamingmediausesa____servicenormally.A.TCPB.UDPC.BothTCPandUDPD.Noneofabove58.TheUDPheaderhasonly____fields.A.2B.4C.1D.359.WhichofthefollowingdoesnotincludedinUDPheader.A.SourceportnumberB.DestinationportnumberC.ChecksumD.Sequencenumber60.Whichofthefollowingisnotapipeliningprotocol.A.Rdt1.0B.Go-Back-NC.SelectiverepeatD.TCP61.InthefollowingfourdescriptionsaboutMSSandMTU,whichoneisnotcorrect? A.TheMSSisthemaximumamountofapplication-layerdatainthesegmentB.TheMSSisthemaximumsizeoftheTCPsegmentincludingheadersC.TheMSSistypicallysetbyMTUD.TheMTUmeansthelargestlink-layerframe62.Thejobofgatheringdatachunks,encapsulatingeachdatachunkwithheaderinformationtocreatesegmentsandpassingthesegmentstothenetworkiscalled____.A.multiplexingB.de-multiplexingC.forwardingD.routing63.Inthefollowingfourdescriptionsabouttherelationshipbetweenthetransportlayerandthenetworklayer,whichoneisnotcorrect?A.Thetransport-layerprotocolprovideslogicalcommunicationbetweenhostsB.Thetransport-layerprotocolprovideslogicalcommunicationbetweenprocessesC.Theservicesthatatransport-layerprotocolcanprovideareoftenconstrainedbytheservicemodelofthenetwork-layerprotocolD.Acomputernetworkmaymakeavailablemultipletransportprotocols64.Supposethefollowingthree8-bitbytes:01010101,01110000,01001100.What’sthe1scomplementofthesumofthese8-bitbytes?A.00010001B.11101101C.00010010D.1000100065.Thefollowingfourdescriptionsaboutmultiplexingandde-multiplexing,whichoneiscorrect?A.AUDPsocketisidentifiedbyatwo-tuplesconsistingofasourceportnumberandadestinationportnumber.B.IftwoUDPsegmenthavedifferentsourceportnumber,theymaybedirectedtothesamedestinationprocess.C.IftwoTCPsegmentswithdifferentsourceportnumber,theymaybedirectedtothesamedestinationprocess.D.IftwoTCPsegmentswithsamedestinationIPaddressanddestinationportnumber,theymustbethesameTCPconnection.66.UDPandTCPbothhavethefieldsexcept____.A.sourceportnumberB.destinationportnumberC.checksumD.receivewindow67.IfwedefineNtobethewindowsize,basetobethesequencenumberoftheoldestunacknowledgedpacket,andnext-seq-numtobethesmallestunusedsequencenumber,thentheinterval[nextseqnum,base+N-1]correspondstopacketthat____.A.canbesentimmediatelyB.havealreadybeentransmittedandacknowledgedC.cannotbeused D.havebeensentbutnotyetacknowledged68.WhichofthefollowingaboutTCPisnotcorrect?A.ItisaconnectionlessprotocolB.Point-to-pointprotocolC.Reliable,in-orderbytesteamprotocolD.Pipelinedprotocol69.WhichofthefollowingaboutTCPisnotcorrect?A.ItisaconnectionlessprotocolB.fullduplexdatatransferprotocolC.connection-orientedprotocolD.flowcontrolledprotocol70.Themaximumamountofdatathatcanbegrabbedandplacedinasegmentislimitedbythe____.A.Maximumsegmentsize(MSS)B.MTUC.SequencenumberD.Checksum71.TheMSSistypicallysetbyfirstdeterminingthelengthofthelargestlink-layerframethatcanbesentbythelocalsendinghost(theso-called____),andthenwillfitintoasinglelink-layerframe.A.Maximumsegmentsize(MSS)B.MTUC.SequencenumberD.Checksum72.TheMSSisthemaximumamountof____layerdatainthesegment,notthemaximumsizeoftheTCPsegmentincludingheaders.A.ApplicationB.TransportC.NetworkingD.Link73.Whichofthefollowingfieldisnotusedforconnectionsetupandteardown?A.SequencenumberB.TSTC.SYND.FIN74.____isthebytestreamnumberoffirstbyteinthesegment.A.SequencenumberB.ACKnumberC.ChecksumD.portnumber75.____isthebytesequencenumbersofnextbyteexpectedfromotherside.A.SequencenumberB.ACKnumberC.Checksum D.portnumber76.BecauseTCPonlyacknowledgesbytesuptothefirstmissingbyteinthestream,TCPissaidtoprovide____acknowledgements.A.CumulativeB.SelectiveC.SingleD.Negative77.Fastretransmitmeansinthecasethat____duplicateACK-sarereceived,theTCPsenderresendsegmentbeforetimerexpires.A.3B.4C.5D.678.TCP____meanssenderwon’toverflowreceiver’sbufferbytransmittingtoomuch,toofast.A.FlowcontrolB.CongestioncontrolC.ReliabledatatransferD.Connection-orientedservice79.TCPprovidesflowcontrolbyhavingthesendermaintainavariablecalledthe____.A.ReceivewindowB.CongestionwindowC.SlidingwindowD.buffer80.HowdoesTCPsenderperceivecongestion?A.TimeoutB.3duplicateACK-sC.BothAandBD.Noneofabove81.Transportprotocolsrunin____.A.ServersB.ClientsC.RoutersD.Endsystems82.WhichofthefollowingservicesisnotprovidedbyTCP?A.DelayguaranteesandbandwidthguaranteesB.ReliabledatatransfersandflowcontrolsC.CongestioncontrolsD.In-orderdatatransfers83.WhichservicedoesUDPnotprovide?A.multiplexingB.de-multiplexingC.error-detectionD.error-correction 84.TherearethreemajoreventsrelatedtodatatransmissionandretransmissionintheTCPsender,whichoneisnotinit?A.datareceivedfromapplicationaboveB.de-multiplexingsegmentC.timertimeoutD.ACKreceipt85.WhichofthefollowingapplicationsnormallyusesUDPservices?A.SMTPB.StreamingmultimediaC.FTPD.HTTP86.WhichofthefollowingaboutTCPconnectionisnotcorrect?A.ItisabroadcastconnectionB.Itisapoint-to-pointconnectionC.ItisapipelinedconnectionD.Itisafullduplexconnection87.TheSYNsegmentisusedfor____.A.TCPconnectionsetupB.TCPflowcontrolC.TCPcongestioncontrolD.ClosingaTCPconnection88.Whichservicehelpspreventtheinternetfromenteringastateofgridlock?A.reliabledatatransferB.flowcontrolC.congestioncontrolD.handshakingprocedure89.TheInternet’s_____isresponsibleformovingpacketsfromonehosttoanother.A.applicationlayerB.transportlayerC.networklayerD.linklayer90.Inthefollowingapplications,whichoneisabandwidth-sensitiveapplication?A.E-mailB.webapplicationC.real-timeaudioD.filetransfer91.Inthefollowingapplications,whichoneusesUDP?A.E-mailB.webapplicationC.filetransferD.DNS92.Inthefollowingfourdescriptions,whichoneiscorrect?A.Ifonehost’stransportlayerusesTCP,thenitsnetworklayermustusevirtual-circuitnetwork.B.Datagramnetworkprovidesconnectionservice C.Thetransport-layerconnectionserviceisimplementedintherouterD.Thenetwork-layerconnectionserviceisimplementedintherouteraswellasintheendsystem.93.____isaspeeding-matchingservice---matchingtheratewhichthesenderissendingagainsttherateatwhichthereceivingapplicationisreading.A.congestioncontrolB.flowcontrolC.sliding-windowcontrolD.variablecontrol94.InthefollowingfourdescriptionsaboutRcv-Window,whichoneiscorrect?A.ThesizeoftheTCPRcvWindowneverchangesthroughoutthedurationoftheconnectionB.ThesizeoftheTCPRcvWindowwillchangewiththesizeoftheTCPRcvBufferC.ThesizeoftheTCPRcvWindowmustbelessthanorequaltothesizeoftheTCPRcvBufferD.SupposehostAsendsafiletohostBoveraTCPconnection,thenumberofunacknowledgedbytesthatAsendscannotexceedthesizeofthesizeoftheRcvWindow.95.Thereare6flagfields.Whichoneistoindicatethatthereceivershouldpassthedatatotheupperlayerimmediately?A.PSHB.URGC.ACKD.RST96.SupposetheTCPreceiverreceivesthesegmentthatpartiallyorcompletelyfillsingapinreceiveddata,itwill____.A.immediatelysendACKB.immediatelysendduplicateACKC.waitsometimeforarrivalofanotherin-ordersegmentD.sendsinglecumulative97._____imposesconstrainontherateatwhichaTCPsendercansendtrafficintothenetwork.A.slidingwindowB.congestionwindowC.receivewindowD.variablewindow98.Flowcontrolandcongestioncontrolaresameatthattheyalllimittherateofthesender,butdifferinthat____.A.flowcontrollimitsitsratebythesizeofRcvWindow,butcongestioncontrolbythetrafficonthelinkB.congestioncontrollimitsitsratebythesizeofRcvWindow,butflowcontrolbythetrafficonthelinkC.flowcontrolmainlyisaccomplishedbythesender,butcongestioncontrolbythereceiver.D.flowcontrolmainlyisaccomplishedbythereceiver,butcongestioncontrolbythelink. 99.Thisjobofdeliveringthedatainatransport-layersegmenttothecorrectsocketiscalled____.A.multiplexingB.de-multiplexingC.forwardingD.routing100.IfwedefineNtobethewindowsize,basetobethesequencenumberoftheoldestunacknowledgedpacket,andnext-seq-numtobethesmallestunusedsequencenumber,thentheinterval[base,nextseqnum-1]correspondstopacketthat____.A.canbesentimmediatelyB.havealreadybeentransmittedandacknowledgedC.cannotbeusedD.havebeensentbutnotyetacknowledged101.____arethetwotypesoftransportservicesthattheInternetprovidestotheapplications.A.TCPandUDPB.connection-orientedandconnectionlessserviceC.TCPandIPD.reliabledatatransferandflowcontrol102.Inthefollowingdescriptionsaboutpersistentconnection,whichoneisnotcorrect?A.TheserverleavestheTCPconnectionopenaftersendingaresponseB.EachTCPconnectionisclosedaftertheserversendingoneobjectC.Therearetwoversionsofpersistentconnection:withoutpipeliningandwithpipeliningD.ThedefaultmodeofHTTPusespersistentconnectionwithpipelining103.ThefieldofLengthinUDPsegmentspecifiesthelengthof____.A.theUDPsegment,notincludingtheheaderB.theUDPsegment,includingtheheaderC.theUDPsegment’sheaderD.theLengthfield104.InTCPsegmentheader,whichfieldcanimplementthereliabledatatransfer?A.sourceportnumberanddestinationportnumberB.sequencenumberandACKnumberC.urgentdatapointerD.Receivewindow105.InthefollowingfourdescriptionsaboutTCPconnectionmanagement,whichoneisnotcorrect?A.EitherofthetwoprocessesparticipatinginaTCPconnectioncanendtheconnectionB.IftheFINbitissetto1,itmeansthatitwantstoclosetheconnectionC.Inthefirsttwostepofthethree-wayhandshake,theclientandserverrandomlychooseaninitialsequencenumberD.Inthethreesegmentsofthethree-wayhandshake,theSYNbitmustbesetto1106.SupposehostAsendstwoTCPsegmentsbacktobacktohostBoveraTCPconnection.Thefirstsegmenthassequencenumber42,andthesecondhassequencenumber110.Ifthe1stislostand2ndarrivesathostB.Whatwillbetheacknowledgmentnumber?A.43B.ACK42C.109D.ACK110 1.ConsidersendinganobjectofsizeO=500,000bytesfromservertoclient.LetS=500bytesandRTT=0.2s.Supposethetransportprotocolusesstaticwindowswithwindowsize5.Foratransmissionrateof100Kbps,determinethelatencyforsendingthewholeobject.RecallthenumberofwindowsK=O/WS),andthereisK-1stalledstate(thatisidletimegaps).K=O/(WS)=500*8*1000/(5*5000*8)=200Latency=2RTT+O/R+(K-1)(S/R+RTT-WS/R)=0.4+500*1000*8/100000+(200-1)(500*8/100000+0.2-5*500*8/100000)=48.36s2.ConsiderthefollowingplotofTCPcongestionwindowsizeasafunctionoftime.14180263000264810121620222402832CongestionwindowsizeTransmissionround481216Fillintheblanksasfollow:a)TheinitialvalueofThresholdatthefirsttransmissionroundis12b)ThevalueofThresholdatthe11sttransmissionroundis_8_.c)ThevalueofThresholdatthe21sttransmissionroundis_7_.d)Afterthe9thtransmissionround,segmentlossdetectedby_A_.A.TimeoutB.TripleduplicateACKe)Afterthe19thtransmissionround,segmentlossdetectedby_B.A.TimeoutB.TripleduplicateACKf)During_5_transmissionround,the18thsegmentissent.3.ConsidertheTCPreliabledatatransferinthegivengraph.IfinSegment1’sSequencenumber=10,data=“AC”,pleasefillinthefollowingblanks.a)InSegment2,ACKnumber=_12_;b)InSegment3,Sequencenumber=_12_;data=“0123456789”c)Iftherearesomebitscorruptedinsegment3whenitarrivesHostB,thentheACKnumberinSegment5is12;andtheACKnumberinSegment6is22. 13462574.TheclientAwantstorequestaWebpagefromServerB.SupposetheURLofthepageis172.16.0.200/experiment,andalsoitwantstoreceiveFrenchversionofobject.Thetime-sequencediagramisshownbelow,pleasefillintheblanks.12345Packet①toPacket③areTCPconnection’ssegment,then:Packet①:a.SYNflagbit=1b.ACKflagbit=0Sequencenumber=92Packet②:SYNflagbit=1c.ACKflagbit=1Sequencenumber=100Packet③:d.SYNflagbit=0ACKflagbit=1e.Sequencenumber=9355.ConsidersendinganobjectofsizeO=100Kbytesfromservertoclient.LetS=536bytesand RTT=100msec.SupposethetransportprotocolusesstaticwindowswithwindowsizeW:(1)Foratransmissionrateof25kbps,determinetheminimumpossiblelatency.Determinetheminimumwindowsizethatachievesthislatency;(2)Repeat(1)for100kbps.Solution:(1)Latency=2RTT+O/R=2*0.1+100*8/25=0.2+32=32.2(s)W*S/R>S/R+RTT----W>1.6,soW=2(2)Latency=2RTT+O/R=2*0.1+100*8/100=0.2+8=8.2(s)W*S/R>S/R+RTT----W>3.3,soW=46.ConsiderthefollowingplotofTCPcongestionwindowsizeasafunctionoftime.Pleasefillintheblanksasbelow.14182630026481012162022242832CongestionwindowsizeTransmissionround481216a)TheinitialvalueofThresholdatthefirsttransmissionroundis_12_.b)ThevalueofThresholdatthe11thtransmissionroundis_8.c)ThevalueofThresholdatthe21sttransmissionroundis_7_.d)Afterthe9thtransmissionround,timeoutoccurs.e)Afterthe19thtransmissionround,3tripleACKaredetected. Chapter4TheNetworkLayer1.Whatisthenameofanetwork-layerpacket?（C）A.messageB.segmentC.datagramD.frame2.Whatarethetwomostimportantnetwork-layerfunctionsinadatagramnetwork?（A）A.forwarding&routingB.forwarding&filteringC.routing&detectingD.routing&checking3.Whenapacketarrivesatarouter’sinputlink,theroutermustmovethepackettotheappropriateoutputlink,thisactioniscalled____?（A）A.ForwardingB.routingC.cutthroughD.filtering4.Thenetworklayermustdeterminethepathtakenbypacketsastheyflowfromasendertoareceiver.Thisactioniscalled____?（B）A.ForwardingB.routingC.cutthroughD.examine5.Arouterforwardsapacketbyexaminingthevalueofafieldinthearrivingpacket’sheader,andthenusingthisvaluetoindexintotherouter’sforwardingtable,thisvalueis?（A）A.destinationIPaddressB.sourceIPaddressC.destinationMACaddressD.sourceMACaddress6.IPbelongsto____layer?（B）A.transportB.networkC.datalinkD.physical7.Whichlayerprovideshost-to-hostservices?（B）A.transportB.networkC.datalinkD.physical8.Whichlayerprovidesaconnectionservicecalledvirtual-circuitnetworksandaconnectionlessservicecalleddatagramnetworks?（B）A.transport B.networkC.datalinkD.physical9.IPV4hasa___bitaddress?（C）A.48B.16C.32D.6410.MACaddressis____bits?（A）A.48B.16C.32D.6411.TheInternet’snetworklayerhasthreemajorcomponents,thefirstcomponentistheIPprotocol,thesecondcomponentistheroutingprotocol,thefinalcomponentis____?（D）A.forwardingB.addresstranslationC.checkD.ICMP12.HowmanybitsspecifytheIPprotocolversioninadatagram?（C）A.1bitB.2bitsC.4bitsD.8bits13.MostIPV4datagramdonotcontainoptionfield,howmanybytesaheaderhasinatypicalIPdatagram?（D）A.4bytesB.8bytesC.16bytesD.20bytes14.HowmanybitsusedinIPdatagramexpresstotallengthoftheIPdatagram?（C）A.4bitsB.8bitsC.16bitsD.20bits15.Data-gramsarerarelylargerthan____?（A）A.1500bytesB.65535bytesC.500bytesD.1024bytes16.NewversionofIP----IPV6doesnotallowfragmentin____?（A）A.RouterB.HostC.Bothofabove D.Noneofabove17.HowdoestheTTLchangedbyoneeachtimethedatagramisprocessedbyarouter?（A）A.decreaseB.increaseC.nochangeD.always018.WhichlayerprotocolisindicatedbythevalueofprotocolfieldinIPdatagram?（B）A.applicationB.transportC.networkD.datalink19.IPoptionisdroppedinthe____header.（A）A.IPv6B.IPv4C.TCPD.UDP20.ThedatafieldinIPdatagramcancarrymanytypesofdataexcept____.（D）A.TCPB.UDPC.ICMPD.MAC21.ICMPisusedfor____?（B）A.ReliabledatatransferB.ErrorreportingC.FlowcontrolD.Congestioncontrol22.SupposeyoureceiveanIPdatagramfromonelinkandcheckyourforwardingtabletodeterminetheoutgoinglink,butthisoutgoinglinkhasanMTUthatissmallerthanthelengthofIPdatagram.Whichtechnologywillbeused?（C）A.resendB.discardC.fragmentD.none23.ThedesignerofIPv4decidedtoputthejobofdatagramreassemblyin____.（D）A.routerB.switchC.hubD.endsystem24.IPaddressingassignsanaddressto223.10.198.250/29,thenetworkaddressforthisnetworkis____.（A）A.223.10.198.248B.223.10.198.250C.223.10.198.0D.223.10.0.0 25.Ifalldata-gramsarrivingattherouterfromWANhavethesamedestinationIPaddress,thenhowdoestherouterknowtheinternalhosttowhichitshouldforwardagivendatagram?Thetrickistouse____tableatrouter,andincludeportnumbersaswellasIPaddressinthetableentries.（D）A.routingB.forwardingC.ARPD.NATtranslation26.WhenrunningaTelnet,FTP,orHTTPsession,youmayhaveencounteredanerrormessagesuchas“Destinationnetworkun-reachable”,Thismessagehaditsoriginin__.（C）A.IGMPB.EGPC.ICMPD.BGP27.Thewell-knownpingprogramsendsan(a)____type8code0messagetothespecifiedhost.Thedestinationhostsseeingtheechorequest,sendbackatype0code0ICMPechoreply.（A）A.ICMPB.IGMPC.TCPD.UDP28.Tracer-outisimplementedwith____messages.（D）A.IGMPB.TCPC.UDPD.ICMP29.ThestandardTracer-outprogramactuallysendssetsof__packetswiththesameTTL.（C）A.oneB.twoC.threeD.four30.IPv6increasesthesizeoftheIPaddressfrom32bitto____bit.（B）A.64B.128C.256D.51231.HowmanybytesarethereinheaderofIPv6?（C）A.8B.20C.40D.3232.IPv6doesnotallowforfragmentationandreassemblyatinter-media____.（A）A.routersB.switches C.endsystemD.hubs33.Fromsendertoreceivers,allpacketswilltakethesamepath,thisisweusea__service.（B）A.datagramB.VCC.circuitD.Ethernet34.____meansmovingpacketsfromrouter’sinputporttoappropriaterouteroutputport?（A）A.forwardingB.filteringC.routingD.switching35.____meansdeterminingroutetakenbypacketsfromsourcetodestination?（C）A.forwardingB.filteringC.routingD.switching36.Arouterworksin____layer?（A）A.NetworkingB.DatalinkC.ApplicationD.Physical37.Aswitchworksin____layer?（B）A.NetworkingB.DatalinkC.ApplicationD.Physical38.Networkinglayerprovidesservicesbetweentwo____.（A）A.HostsB.ProcessesC.ApplicationsD.Machines39.Linklayerprovidesservicesbetweentwo____.（B）A.HostsB.ProcessesC.ApplicationsD.Machines40.Theinternet’snetworklayerprovidesasingleservice----thatis____.（C）A.ReliabledatatransferB.FlowcontrolC.CongestioncontrolD.Best-effort-service41.Datagramnetworkprovidesnetwork-layer____.（A）A.connectionlessservice B.connectionserviceC.bothofaboveD.neitherofAandB42.VCnetworkprovidesnetwork-layer____.（B）A.connectionlessserviceB.connectionserviceC.bothofaboveD.neitherofAandB43.InVCnetwork,eachpacketcarries____.（A）A.VCidentifierB.destinationhostaddressC.IPaddressD.Macaddress44.AVCconsistsofthreepart,thisthreepartsdonotinclude____.（D）A.PathfromsourcetodestinationB.VCnumbers,onenumberforeachlinkalongpathC.EntriesinforwardingtablesinroutersalongpathD.Destinationaddress45.In____networking,aseriesofpacketmayfollowdifferentpathsandmayarriveoutoforder?（A）A.DatagramB.VCC.TCPD.Noneofabove46.Theinternetisa(an)____network?（A）A.DatagramB.VCC.BothofaboveD.Noneofabove47.Thefourcomponentsofarouterdonotinclude____?（D）A.InputandoutputportsB.SwitchfabricC.RoutingprocessorD.Switchingprocessor48.Therearethreekindsofswitchfabricforarouternormally,thosethreeswitchfabricdonotincludes____?（D）A.SwitchingviamemoryB.SwitchingviaabusC.SwitchingviaanInterconnection-NetworkD.Packetswitching49.Whichofthefollowingprotocolisusedforerrorreporting?（A）A.ICMPB.TCPC.IP D.UDP50.Whichofthefollowingisnotaroutingprotocol?（A）A.TCPB.RIPC.OSPFD.BGP51.IPV4hasa___bitsaddress?（A）A.32B.64C.16D.12852.IPaddressisidentifierfor____.（C）A.HostB.RouterinterfaceC.BothofaboveD.Noneofabove53.“233.1.1.0/24”,wherethe/24notation,sometimesknownasa____.（A）A.SubnetmaskB.NetworkingaddressC.HostaddressD.Noneofabove54.Subnetswithan8-,____-,and24-bitsubnetaddresseswereknowasclassA,B,andCnetworksrespectively.（D）A.9B.10C.12D.1655.IPV6hasa___bitsaddress?（D）A.32B.64C.16D.12856.____meansthatIPv6nodesalsohaveacompleteIPv4implementationaswell?（A）A.DualstackB.TunnelingC.BridgeconnectionD.Forwarding57.____meansthatIPv6carriedaspayloadinIPv4data-gramamongIPv4routers?（B）A.DualstackB.TunnelingC.BridgeconnectionD.Forwarding58.Typicallyahostisattacheddirectlytoonerouter,the____forthehost.（A）A.Defaultrouter B.SourcerouterC.DestinationrouterD.Corerouter59.Thedefaultrouterofthesourcehostisknownas____.（B）A.DefaultrouterB.SourcerouterC.DestinationrouterD.Corerouter60.Thedefaultrouterofthedestinationhostisknownas____.（C）A.DefaultrouterB.SourcerouterC.DestinationrouterD.Corerouter61.Apathbetweenthesourceanddestinationthathasbeastcostisknownas____.（A）A.LeastcostpathB.ShortestpathC.LargestcostpathD.Noneofabove62.Thepathwiththesmallestnumberoflinksbetweenthesourceandthedestinationisknownas____.（B）A.LeastcostpathB.ShortestpathC.LargestcostpathD.Noneofabove63.WhichoffollowingaboutDVisnotcorrect?（B）A.IterativeB.SynchronousC.DistributedD.Self-terminating64.Whichofthefollowingisnotintra-ASroutingprotocol?（D）A.RIPB.OSPFC.IGRPD.BGP65.RIPisakindof____algorithm.（A）A.DVB.LSC.BothofaboveD.NeitherofAandB66.OSPFisakindof____algorithm.（B）A.DVB.LSC.BothofaboveD.NeitherofAandB 67.Therouterinnon-backboneareasandperformonlyintra-ASroutingisknownas__.（A）A.InternalroutersB.AreaborderroutersC.BackboneroutersD.Boundaryrouters68.__“summarize”distancestonetsinownarea,advertisetootherAreaBorderrouters.（B）A.InternalroutersB.AreaborderroutersC.BackboneroutersD.Boundaryrouters69.____runsOSPFroutinglimitedtobackbone.（C）A.InternalroutersB.AreaborderroutersC.BackboneroutersD.Boundaryrouters70.____connecttootherAS’s.（D）A.InternalroutersB.AreaborderroutersC.BackboneroutersD.Boundaryrouters71.Whichofthefollowingisaninter-autonomoussystemroutingprotocol?（D）A.RIPB.OSPFC.IGRPD.BGP72.____meanssendingapackettoallothernodesinthenetwork.（A）A.BroadcastB.MulticastC.Any-castD.Uni-cast73.A____packetisdeliveredtoonlyasubsetofnetworknodes.（B）A.BroadcastB.MulticastC.Any-castD.Uni-cast74.Meansthattheswitchmustreceivetheentirepacketbeforeitcanbegintotransmitthefirstbitofthepacketontotheoutboundlink.（A）A.store-and-forwardtransmissionB.FDMC.End-to-endconnectionD.TDM75.Datagramnetworksandvirtual-circuitnetworksdifferin____.（C）A.Datagramnetworksarecircuit-switchednetworks,andvirtual-circuitnetworksarepacket-switchednetworks. B.Datagramnetworksarepacket-switchednetworks,andvirtual-circuitnetworksarecircuit-switchednetworks.C.Datagramnetworksusedestinationaddressesandvirtual-circuitnetworksuseVC.Numberstoforwardpacketstowardtheirdestination.D.DatagramnetworksuseVC.Numbersandvirtual-circuitnetworksusedestinationaddressestoforwardpacketstowardtheirdestination.76.TheInternet’snetworklayerisresponsibleformovingnetwork-layerpacketsknownas____fromonehosttoanother.（B）A.frameB.datagramC.segmentD.message77.Theprotocolsofvariouslayersarecalled____.（A）A.theprotocolstackB.TCP/IPC.ISPD.networkprotocol78.Thetwoimportantnetwork-layerfunctionsare____.（B）A.multiplexingandde-multiplexingB.routingandforwardingC.lookupandforwardingD.routingandIPaddressing79.Thevirtualcircuitincludesthreeidentifiablephasesbut____.（C）A.setupB.datatransferC.forwardingVCnumbersD.teardown80.Therearesomewaystoaccomplishtheswitchingintherouter,whichoneisnotincluded?（C）A.switchingviamemoryB.switchingviaabusC.switchingviahubD.switchingviaaninterconnection81.Intherouter,thepacketqueuescanformat____.（C）A.institutionalcacheB.switchfabricC.inputportD.routingprocessor82.InIPV4datagramheader,whichfieldistoensurethatdatagramdonotcirculateforeverinthenetwork?（B）A.typeofserviceB.time-to-liveC.headerchecksumD.version 83.SupposeoneIPdatagramof5,000bytes(20bytesofIPheader)anditmustbeforwardedtoalinkwithanMTUof1,500bytes,theoffsetandflagofthesecondfragmentinheaderare____.（B）A.185,0B.185,1C.370,1D.370,084.GiventheIPaddress202.96.104.8/20,itssubnetaddressis____.（B）A.202.96.104.0B.202.96.96.0C.202.96.104.255D.202.96.111.25585.Ifthesubnetmaskis255.255.240.0,thenhowmanybitsindicatethehostaddress?（C）A.20B.24C.12D.1686.Inthefollowingfourfields,whichisinIPV6headerbutnotinIPV4?（D）A.sourceaddressB.destinationaddressC.versionD.flowlabel87.Onehostisattacheddirectlytoonerouter,therouteris____.（C）A.NATrouterB.gatewayrouterC.first-hoprouterD.intervalrouter88.TheInternet’snetworklayerincludesthefollowingcomponentsbut____.（D）A.IPprotocolB.theInternetMessageControlProtocolC.RoutingProtocolD.ChannelPartitioningProtocol89.Inthefollowingprotocols,whichoneisinter-ASroutingprotocol?（C）A.RIPB.OSPFC.BGPD.ICMP90.Inthefollowingfourdescriptionsaboutautonomoussystem,whichoneisnotcorrect?（D）A.Anautonomoussystemisacollectionofroutersunderthesameadministrativeandtechnicalcontrol.B.Allroutersinanautonomoussystemrunthesameroutingprotocol.C.Theroutingalgorithmrunningwithinanautonomoussystemiscalledanintra-ASroutingprotocol. D.TheroutersthatconnectAS-stoeachotherarecalleddefaultrouter.91.IntheloopoftheDijkstra’salgorithm,fornodex,addytoN’,andupdatethecostofy’sneighborv,thenD(v)is____.（C）A.c(x,v)B.min{D(v),D(x)+c(x,v)}C.min{D(v),D(y)+c(y,v)}D.c(y,v)92.ConsiderthedataDis01110010001,ifuseevenparitycheckingapproach,theparitybitis(),ifuseoddparitycheckingapproach,theparitybitis____.（C）A.0,0B.0,1C.1,0D.1,193.Theabilitytodeterminetheinterfacestowhichaframeshouldbedirected,andthendirectingtheframetothoseinterfacesis____.（B）A.filteringB.forwardingC.self-learningD.optimalrouting94.Giventhatcostsareassignedtovariousedgeinthegraphabstraction.Inthefollowingfourdescriptions,whichoneisnotcorrect?（D）A.Theshortestpathisthepathwithsmallestnumberoflinksbetweenthesourceanddestination.B.Theleastcostpathisnotalwaystheshortestpath.C.Ifalledgeshavesamecost,theleastcostpathmustbetheshortestpath.D.Ifalledgeshavevariouscosts,theleastcostpathmustnotbetheshortestpath.95.GiventheIPaddress202.96.104.8/20,itsbroadcastaddressis____.（D）A.202.96.104.0B.202.96.96.0C.202.96.104.255D.202.96.111.25596.Ifthesubnetmaskis255.240.0.0,thenhowmanybitsindicatethehostaddress?（A）A.20B.12C.24D.1697.InIPV6datagramheader,thefieldNext-headerisequivalenttothefieldinIPV4.（A）A.upper-layerprotocolB.time-to-liveC.headerchecksumD.version98.Foronehost,itssourcerouterisalsocalled____.（C）A.NATrouterB.gatewayrouterC.first-hoprouterD.intervalrouter99.Inthefollowingfourdescriptionsaboutlink-state(LS)algorithm,whichoneisnotcorrect? （B）A.TheLSalgorithmmustbeawareofthecostofeachlinkinthenetwork.B.TheLSalgorithmisadecentralizedalgorithmC.TheLSalgorithmcomputestheleastcostpathbetweenasourceanddestinationusingcompleteglobalknowledgeaboutthenetworkD.ThecalculationofLSalgorithmcanberunatonesiteormultiplesites100.IntheinitializationoftheDijkstra’salgorithm,fornodex,ifyisnotaneighborofx,thenD(y)is____.（C）A.0B.1C.∞D.c(x,y)101.InDValgorithm,whenonenodeupdatesitsdistancevector,itmust____.（A）A.sendtheupdatedroutingtabletoitsneighborsB.sendtheupdatedroutingtabletoallthenodesintheASC.sendtheupdatedroutingtableatrandomD.donothing102.NowwehadknownIPaddressis211.197.3.158/26,Pleasecompute:(1)Networkaddress?Networkaddressis211.197.3.128(2)Broadcastaddress?Broadcastaddressis211.197.3.191(3)Howmanyhostsarethereinthenetwork?Thereare62hostsinthenetwork(4)FisthostIPaddress?FisthostIPaddressis211.197.3.129(5)LasthostIPaddress?LasthostIPaddressis211.197.3.190103．Forthegiventopologyofthenetwork,useDijstra’sshortestpathalgorithmtocomputetheshortestpathfromAtoallnetworknodes.GiveashortestpathtreeandnodeA’sroutingtable.1EABDCF12522153EABDCF12211Answer:DestinationNextBCCCDDEEFE 104．Thetopologyofanetworkshownasbelow.UsingLinkStateroutingalgorithmtocalculatetheroutingtableinthenodeA.ThevectorsarrivetonodeCasbellow:B:(4,0,8,12,6,2);D:(13,10,6,0,9,10);E:(7,6,3,9,0,14).ThedelaysmeasuredfromCtoB,D,Eare4,2,and3separately.UpdaterouterC’sroutetableplease.ABCDFEAnswer:dCB+dBA4+4dCA=mindCD+dDA=min2+13=8sCA=BdCE+dEA3+7dCB+dBB4+0dCB=mindCD+dDB=min2+10=4sCB=BdCE+dEB3+6dCB+dBD4+12dCD=mindCD+dDD=min2+0=2sCD=DdCE+dED3+9dCB+dBE4+6dCE=mindCD+dDE=min2+9=3sCE=EdCE+dEE3+0dCB+dBF4+2dCF=mindCD+dDF=min2+10=6sCF=BdCE+dEF3+14routerC’sroutetableDestinationNetworkDcScA8BB4BC0--D2DE3EF6B Chapter5TheLinkLayerandLocalAreaNetwork1.A(D)protocolisusedtomoveadatagramoveranindividuallink.A.application-layerB.transport-layerC.network-layerD.link-layer2.Theunitsofdataexchangedbyalink-layerprotocolarecalled(B).A.datagramsB.framesC.segmentsD.messages3.Whichofthefollowingprotocolsisnotalink-layerprotocol?(D)A.EthernetB.PPPC.HDLCD.IP4.Inthefollowingfourdescriptions,whichoneisnotcorrect?(C)A.link-layerprotocolhasthenode-to-nodejobofmovingnetwork-layerdatagramsoverasinglelinkinthepath.B.Theservicesprovidedbythelink-layerprotocolsmaybedifferent.C.Adatagrammustbehandledbythesamelink-layerprotocolsonthedifferentlinksinthepath.D.Theactionstakenbyalink-layerprotocolwhensendingandreceivingframesincludeerrordetection,flowcontrolandrandomaccess.5.Whichofthefollowingservicescannotofferedbyalink-layerprotocol?(A)A.congestioncontrolB.LinkAccessC.ErrorcontrolD.Framing6.(B)protocolservestocoordinatetheframetransmissionsofthemanynodeswhenmultiplenodesshareasinglebroadcastlink.A.ARPB.MACC.ICMPD.DNS7.Inthefollowingfourdescriptionsabouttheadapter,whichoneisnotcorrect?(D)A.TheadapterisalsocalledasNIC.B.Theadapterisasemi-autonomousunit.C.Themaincomponentsofanadapterarebusinterfaceandthelinkinterface.D.Theadaptercanprovideallthelink-layerservices.8.ConsiderCRCerrorcheckingapproach,thefourbitgeneratorGis1011,andsupposethatthedataDis10101010,thenthevalueofRis(A). A.010B.100C.011D.1109.Inthefollowingfourdescriptionsaboutrandomaccessprotocol,whichoneisnotcorrect?(A)A.InslottedALOHA,nodescantransmitatrandomtime.B.InpureALOHA,ifaframeexperiencesacollision,thenodewillimmediatelyretransmititwithprobabilityp.C.ThemaximumefficiencyofaslottedALOHAishigherthanapureALOHA.D.InCSMA/CD,onenodelistenstothechannelbeforetransmitting.10.InthefollowingdescriptionsaboutMACaddress,whichoneisnotcorrect?(D)A.TheMACaddressistheaddressofonenode’sadapter.B.NotwoadaptershavethesameMACaddress.C.TheMACaddressdoesn’tchangenomatterwheretheadaptergoes.D.MACaddresshasahierarchicalstructure.11.TheARPprotocolcantranslate()into().(C)A.hostname,IPaddressB.hostname,MACaddressC.IPaddress,MACaddressD.broadcastaddress,IPaddress12.ThevalueofPreamblefieldinEthernetframestructureis(C)A.1010101010101010……1010101011111111B.1010101110101011……1010101110101011C.1010101010101010……1010101010101011D.1010101010101010……101010101010101013.TherearefourstepsinDHCP,theDHCPservercancomplete(B).A.DHCPserverdiscoveryB.DHCPserveroffersC.DHCPrequestD.DHCPresponse14.InCSMA/CD,theadapterwaitssometimeandthenreturnstosensingthechannel.Inthefollowingfourtimes,whichoneisimpossible?(D)A.0bittimesB.512bittimesC.1024bittimesD.1028bittimes15.ThemostcommonEthernettechnologiesare10BaseTand100BaseT.“10”and“100”indicate(D).A.themaximumlengthbetweentwoadaptersB.theminimumlengthbetweentwoadaptersC.thetransmissionrateofthechannelD.thetransmissionrateofthenode16.TheprincipalcomponentsofPPPincludebutnot(B). A.framingB.physical-controlprotocolC.link-layerprotocolD.network-layerprotocol17.Inthefollowingfouroptions,whichservicecannotbeprovidedbyswitch?(D)A.filteringB.self-learningC.forwardingD.optimalrouting18.Inthefollowingfourservices,whichonewasberequiredinPPP?(C)A.packetframingB.errordetectionC.errorcorrectionD.multipletypesoflink19.Theabilitytodeterminetheinterfacestowhichaframeshouldbedirected,andthendirectingtheframetothoseinterfacesis(B).A.filteringB.forwardingC.self-learningD.optimalrouting20.In(A)transmission(s),thenodesatbothendsofalinkmaytransmitpacketsatthesametime.A.full-duplexB.half-duplexC.single-duplexD.bothfull-duplexandhalf-duplex21.ConsiderthedataDis01110010001,ifuseevenparitycheckingapproach,theparitybitis(①),ifuseoddparitycheckingapproach,theparitybitis(②).(D)A.①0②1B.①0②0C.①1②1D.①1②022.Inthefollowingfourdescriptionsaboutparitychecks,whichoneiscorrect?(C)A.Single-bitparitycandetectallerrors.B.Single-bitparitycancorrectoneerrors.C.Two-dimensionalparitynotonlycandetectasinglebiterror,butalsocancorrectthaterror.D.Two-dimensionalparitynotonlycandetectanycombinationoftwoerrors,butalsocancorrectthem.23.MACaddressis(B)bitslong.A.32B.48C.128D. 6424.WirelessLANusingprotocol(D).A.IEEE802.3B.IEEE802.4C.IEEE802.5D.IEEE802.1125.Thefollowingprotocolsarebelongingtomultipleaccessprotocolsexceptfor(B).A.channelpartitioningprotocolsB.routingprotocolsC.randomaccessprotocolsD.taking-turnsprotocols26.Whichofthefollowingisnotbelongingtochannelpartitioningprotocols?(A)A.CSMAB.FDMC.CDMAD.TDM27.InthefollowingfourdescriptionsaboutCSMA/CD,whichoneisnotcorrect?(D)A.Anodelistenstothechannelbeforetransmitting.B.Ifsomeoneelsebeginstalkingatthesametime,stoptalking.C.Atransmittingnodelistenstothechannelwhileitistransmitting.D.WithCSMA/CD,thecollisionscanbeavoidedcompletely.28.(B)providesamechanismfornodestotranslateIPaddressestolink-layeraddress.A.IPB.ARPC.RARPD.DNS29.AMACaddressisa(C)address.A.physical-layerB.application-layerC.link-layerD.network-layer30.Whichofthefollowingiscorrect?(D)A.NotwoadaptershavethesameMACaddress.B.MACbroadcastaddressisFF-FF-FF-FF-FF-FF.C.AportablecomputerwithanEthernetcardalwayshasthesameMACaddress,nomatterwherethecomputergoes.D.Alloftheabove31.Inthefollowingfourdescriptions,whichoneisnotcorrect?(D)A.ARPresolvesanIPaddresstoaMACaddress.B.DNSresolveshostnamestoIPaddresses.C.DNSresolveshostnamesforhostsanywhereintheInternet.D.ARPresolvesIPaddressesfornodesanywhereintheInternet.32.IntheLAN,(C)protocoldynamicallyassignIPaddressestohosts.A.DNSB.ARP C.DHCPD.IP33.DHCPprotocolisafour-stepprocess:①DHCPrequest.②DHCPACK.③DHCPserverdiscovery.④DHCPserveroffer(s).Thecorrectsequenceis(C).A.①②③④B.③②①④C.③④①②D.①④③②34.IntheEthernetframestructure,theCRCfieldis(B)bytes.A.2B.4C.8D.3235.IntheEthernetframestructure,theDatafieldcarriesthe(A).A.IPdatagramB.segmentC.frameD.message36.Inthefollowingfourdescriptions,whichoneisnotcorrect?(B).A.Ethernetusesbasebandtransmission.B.AlloftheEthernettechnologiesprovideconnection-orientedreliableservicetothenetworklayer.C.TheEthernet10Base2technologyusesathincoaxialcableforthebus.D.TheEthernet10BaseTtechnologyusesastartopology.37.Ethernet’smultipleaccessprotocolis(B).A.CDMAB.CSMA/CDC.slottedALOHAD.token-passingprotocol38.InthefollowingfourdescriptionsaboutCSMA/CD,whichoneisnotcorrect?(D)A.Anadaptermaybegintotransmitatanytime.B.Anadapternevertransmitsaframewhenitsensesthatsomeotheradapteristransmitting.C.Atransmittingadapterabortsitstransmissionassoonasitdetectsthatanotheradapterisalsotransmitting.D.Anadapterretransmitswhenitdetectsacollision.39.WhichofthefollowingdescriptionsaboutCSMA/CDiscorrect?(D)A.Noslotsareused.B.Itusescarriersensing.C.Itusescollisiondetection.D.Alloftheabove.40.TheEthernet10BaseTtechnologyuses(B)asitsphysicalmedia.A.fiberopticsB.twisted-paircopperwire C.coaxialcableD.satelliteradiochannel41.For10BaseT,themaximumlengthoftheconnectionbetweenanadapterandthehubis(A)meters.A.100B.200C.500D.1042.A(B)isaphysical-layerdevicethatactsonindividualbitsratherthanonframes.A.switchB.hubC.routerD.gateway43.Ahubisa(A)devicethatactsonindividualbitsratherthanonframes.A.physical-layerB.link-layerC.network-layerD.ransport-layer44.Aswitchisa(B)devicethatactsonframe.A.physical-layerB.link-layerC.network-layerD.transport-layer45.Inthefollowingfourdescriptions,whichoneisnotcorrect?(B)A.SwitchescaninterconnectdifferentLANtechnologies.B.HubscaninterconnectdifferentLANtechnologies.C.ThereisnolimittohowlargeaLANcanbewhenswitchesareusedtointerconnectLANsegments.D.ThereisrestrictiononthemaximumallowablenumberofnodesinacollisiondomainwhenhubsareusedtointerconnectLANsegments.46.Theabilitytodeterminewhetheraframeshouldbeforwardedtosomeinterfaceorshouldjustbedroppedis(A).A.filteringB.forwardingC.self-learningD.optimalrouting47.Whichofthefollowingdevicesisnotaplugandplaydevice?(B)A.hubB.routerC.switchD.repeater48.Whichofthefollowingdevicesisnotcut-throughdevice?(B)A.hubB.router C.switchD.repeater49.Inthefollowingfourdescriptions,whichoneisnotcorrect?(C)A.Switchesdonotofferanyprotectionagainstbroadcaststorms.B.Routersprovidefirewallprotectionagainstlayer-2broadcaststorms.C.Bothswitchesandroutersareplugandplaydevices.D.Arouterisalayer-3packetswitch,aswitchisalayer-2packetswitch.50.Whichdevicehasthesamecollisiondomain?(A)A.HubB.SwitchC.RouterD.Bridge51.IEEE802.2protocolbelongto(C)layerA.networkB.MACC.LLCD.physical52.IEEE802.11protocoldefines(C)rules.A.EthernetBusB.wirelessWANC.wirelessLAND.TokenBus53.Indatalink-layer,whichprotocolisusedtosharebandwidth?(D)A.SMTPB.ICMPC.ARPD.CSMA/CD54.WhentwoormorenodesontheLANsegmentstransmitatthesametime,therewillbeacollisionandallofthetransmittingnodeswellenterexponentialback-off,thatisalloftheLANsegmentsbelongtothesame(A).A.collisiondomainB.switchC.bridgeD.hub55.(A)allowsdifferentnodestotransmitsimultaneouslyandyethavetheirrespectivereceiverscorrectlyreceiveasender’sencodeddatabits.A.CDMAB.CSMAC.CSMA/CDD.CSMA/CA56.Becausetherearebothnetwork-layeraddresses(forexample,InternetIPaddresses)andlink-layeraddresses(thatis,LANaddresses),thereisaneedtotranslatebetweenthem.FortheInternet,thisisthejobof(C).A.RIP B.OSPFC.ARPD.IP57.PPPdefinesaspecialcontrolescapebyte,(B).Iftheflagsequence,01111110appearsanywhereintheframe,exceptintheflagfield,PPPprecedesthatinstanceoftheflagpatternwiththecontrolescapebyte.A.01111110B.01111101C.10011001D.1011111058.Thedevice(B)canisolatecollisiondomainsforeachoftheLANsegment.A.modemB.switchC.hubD.NIC59.InthefollowingfourdescriptionsaboutPPP,whichoneisnotcorrect?(A)A.PPPisrequiredtodetectandcorrecterrors.B.PPPisnotrequiredtodeliverframestothelinkreceiverinthesameorderinwhichtheyweresentbythelinksender.C.PPPneedonlyoperateoverlinksthathaveasinglesenderandasinglereceiver.D.PPPisnotrequiredtoprovideflowcontrol.60.InthePPPdataframe,the(C)fieldtellsthePPPreceiverstheupper-layerprotocoltowhichthereceivedencapsulateddatabelongs.A.flagB.controlC.protocolD.checksum61.PPP’slink-controlprotocols(LCP)accomplish(D).A.initializingthePPPlinkB.maintainingthePPPlinkC.takingdownthePPPlinkD.alloftheabove62.ThePPPlinkalwaysbeginsinthestateandendsinthestate.(C)A.open,terminatingB.open,deadC.dead,deadD.dead,terminating63.For(A)linksthathaveasinglesenderatoneendofthelinkandasinglereceiverattheotherendofthelink.A.point-to-pointB.broadcastC.multicastD.alloftheabove64.With(B)transmission,thenodesatbothendsofalinkmaytransmitpacketsatthesame time.A.half-duplexB.full-duplexC.simplex(单工)D.synchronous65.With(A)transmission,anodecannotbothtransmitandreceiveatthesametime.A.half-duplexB.full-duplexC.simplex(单工)D.synchronous66.Whichofthefollowingfunctionscan’tbeimplementedintheNIC?(D)A.encapsulationanddecapsulationB.errordetectionC.multipleaccessprotocolD.routing67.Whichofthefollowingfourdescriptionsiswrong?(C)A.Thebusinterfaceofanadapterisresponsibleforcommunicationwiththeadapter’sparentnode.B.Thelinkinterfaceofanadapterisresponsibleforimplementingthelink-layerprotocol.C.Thebusinterfacemayprovideerrordetection,randomaccessfunctions.D.Themaincomponentsofanadapterarethebusinterfaceandthelinkinterface.68.Foroddparityschemes,whichofthefollowingiscorrect?(B)A.011010001B.111000110C.110101110D.00011011069.(B)dividestimeintotimeframesandfurtherdivideseachtimeframeintoNtimeslots.A.FDMB.TMDC.CDMAD.CSMA70.WithCDMA,eachnodeisassignedadifferent(A).A.codeB.timeslotC.frequencyD.link71.Whichofthefollowingfourdescriptionsaboutrandomaccessprotocolisnotcorrect?(B)A.AtransmissionnodetransmitsatthefullrateofthechannelB.Whenacollisionhappens,eachnodeinvolvedinthecollisionretransmitsatonce.C.BothslottedALOHAandCSMA/CDarerandomaccessprotocols.D.Withrandomaccessprotocol,theremaybeemptyslots.72.PPPdefinesaspecialcontrolescapebyte01111101.Ifthedataisb1b201111110b3b4b5,thevalueis(A)afterbytestuffing.A.b1b20111110101111110b3b4b5 B.b1b20111111001111101b3b4b5C.b5b4b30111111001111101b2b1D.b5b4b30111110101111110b2b173.MACaddressisin(B)ofthecomputer.A.RAMB.NICC.harddiskD.cache74.Whichofthefollowingiswrong?(A)A.ARPtableisconfiguredbyasystemadministratorB.ARPtableisbuiltautomaticallyC.ARPtableisdynamicD.ARPtablemapsIPaddressestoMACaddresses75.NICworksin(B)layer.A.physicalB.linkC.networkD.transport76.InLAN,ifUTPisused,thecommonconnectoris(C).A.AUIB.BNCC.RJ-45D.NNI77.Themodem’sfunction(s)is(are)(C).A.translatesdigitalsignalintoanalogsignalB.translatesanalogsignalintodigitalsignalC.bothtranslatesanalogsignalintodigitalsignalandtranslatesdigitalsignalintoanalogsignalD.translatesonekindofdigitalsignalintoanotherdigitalsignal78.(C)definesToken-Ringprotocol.A.IEEE802.3B.IEEE802.4C.IEEE802.5D.IEEE802.279.(B)definesToken-Busprotocol.A.IEEE802.3B.IEEE802.4C.IEEE802.5D.IEEE802.280.(A)definesCSMA/CDprotocol.A.IEEE802.3B.IEEE802.4C.IEEE802.5D.IEEE802.2 81.Thecomputernetworkthatconcentratedinageographicalarea,suchasinabuildingoronauniversitycampus,is(A).A.aLANB.aMANC.aWAND.theInternet82.TheMACaddressis(B)bitslong.A.32B.48C.128D.25683.WhichofthefollowingfourdescriptionsaboutMACaddressesiswrong?(C)A.aMACaddressisburnedintotheadapter’sROMB.NotwoadaptershavethesameaddressC.Anadapter’sMACaddressisdynamicD.AMACaddressisalink-layeraddress84.WhichofthefollowingfourdescriptionsaboutDHCPiscorrect?(B)A.DHCPisC/SarchitectureB.DHCPusesTCPasitsunderlyingtransportprotocolC.TheIPaddressofferedbyaDHCPserverisvalidforeverD.TheDHCPserverwillofferthesameIPaddresstoahostwhenthehostrequestsanIPaddress85.The(B)fieldpermitsEthernettomultiplexnetwork-layerprotocols.A.preambleB.typeC.CRCD.destinationMACaddress86.For10BaseT,themaximumlengthoftheconnectionbetweenanadapterandthehubis(B)meters.A.50;B.100;C.200;D.50087.Anentryintheswitchtablecontainsthefollowinginformationexceptsfor(D)A.theMACaddressofanodeB.theswitchinterfacethatleadstowardsthenodeC.thetimeatwhichtheentryforthenodewasplacedinthetableD.theIPaddressofanode88.Considerthe4-bitgenerator,Gis1001,andsupposethatDhasthevalue101110000.WhatisthevalueofR?Answer: 89.Considerthefollowinggraphofthenetwork.SupposeHostAwillsendadatagramtoHostB,HostArunOICQonport4000,HostBrunOICQonport8000.AllofARPtablesareuptodate.Enumerateallthestepswhenmessage“Hello”issentfromhostAtohostB.Answer:hostAapplication-layer:HellohostAtransport-layer:40008000HellohostAnetwork-layer:192.168.0.2192.168.1.240008000HellohostAlink-layer:5555-6666-77771111-2222-AAAA192.168.0.2192.168.1.240008000HelloFCS(CRC)routerRE1:1111-2222-BBBB5555-6666-8888192.168.0.2192.168.1.240008000HelloFCS(CRC)hostBnetwork-layer:192.168.0.2192.168.1.240008000HellohostBtransport-layer:40008000HellohostBapplication-layer:Hello'