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Chapter4TheNetworkLayer1．Whatisthenameofanetwork-layerpacket?（）A.messageB.segmentC.datagramD.frame2．Whatarethetwomostimportantnetwork-layerfunctionsinadatagramnetwork?（）A.forwarding&routingB.forwarding&filteringC.routing&detectingD.routing&checking3．Whenapacketarrivesatarouter’sinputlink,theroutermustmovethepackettotheappropriateoutputlink,thisactioniscalled____?（）A.ForwardingB.routingC.cutthroughD.filtering4．Thenetworklayermustdeterminethepathtakenbypacketsastheyflowfromasendertoareceiver.Thisactioniscalled____?（）A.ForwardingB.routingC.cutthroughD.examine5．Arouterforwardsapacketbyexaminingthevalueofafieldinthearrivingpacket’sheader,andthenusingthisvaluetoindexintotherouter’sforwardingtable,thisvalueis?（）A.destinationIPaddressB.sourceIPaddressC.destinationMACaddressD.sourceMACaddress6．IPbelongsto____layer?（）A.transportB.networkC.datalinkD.physical7．Whichlayerprovideshost-to-hostservices?（）A.transportB.networkC.datalinkD.physical8．Whichlayerprovidesaconnectionservicecalledvirtual-circuitnetworksandaconnectionlessservicecalleddatagramnetworks?（）A.transportB.networkC.datalinkD.physical9．IPV4hasa___bitaddress?（）A.48B.16C.32D.6410．MACaddressis____bits?（）A.48B.16C.32D.6411．TheInternet’snetworklayerhasthreemajorcomponents,thefirstcomponentistheIPprotocol,thesecondcomponentistheroutingprotocol,thefinalcomponentis____?（）A.forwardingB.addresstranslationC.checkD.ICMP12．HowmanybitsspecifytheIPprotocolversioninadatagram?（）A.1bitB.2bitsC.4bitsD.8bits13．MostIPV4datagramdonotcontainoptionfield,howmanybytesaheaderhasinatypicalIPdatagram?（）A.4bytesB.8bytesC.16bytesD.20bytes14．HowmanybitsusedinIPdatagramexpresstotallengthoftheIPdatagram?（）A.4bitsB.8bitsC.16bitsD.20bits15．Data-gramsarerarelylargerthan____?（）A.1500bytesB.65535bytesC.500bytesD.1024bytes16．NewversionofIP----IPV6doesnotallowfragmentin____?（）A.RouterB.HostC.BothofaboveD.Noneofabove17．HowdoestheTTLchangedbyoneeachtimethedatagramisprocessedbyarouter?（）A.decreaseB.increaseC.nochangeD.always018．WhichlayerprotocolisindicatedbythevalueofprotocolfieldinIPdatagram?（）A.applicationB.transportC.networkD.datalink19．IPoptionisdroppedinthe____header.（）A.IPv6B.IPv4C.TCPD.UDP20．ThedatafieldinIPdatagramcancarrymanytypesofdataexcept____.（）A.TCPB.UDPC.ICMPD.MAC21．ICMPisusedfor____?（）A.ReliabledatatransferB.ErrorreportingC.FlowcontrolD.Congestioncontrol22．SupposeyoureceiveanIPdatagramfromonelinkandcheckyourforwardingtabletodeterminetheoutgoinglink,butthisoutgoinglinkhasanMTUthatissmallerthanthelengthofIPdatagram.Whichtechnologywillbeused?（）A.resendB.discardC.fragmentD.none23．ThedesignerofIPv4decidedtoputthejobofdatagramreassemblyin____.（）A.routerB.switchC.hubD.endsystem24．IPaddressingassignsanaddressto223.10.198.250/29,thenetworkaddressforthisnetworkis____.（）A.223.10.198.248B.223.10.198.250C.223.10.198.0D.223.10.0.025．Ifalldata-gramsarrivingattherouterfromWANhavethesamedestinationIPaddress,thenhowdoestherouterknowtheinternalhosttowhichitshouldforwardagivendatagram?Thetrickistouse____tableatrouter,andincludeportnumbersaswellasIPaddressinthetableentries.（）A.routingB.forwardingC.ARPD.NATtranslation26．WhenrunningaTelnet,FTP,orHTTPsession,youmayhaveencounteredanerrormessagesuchas“Destinationnetworkun-reachable”,Thismessagehaditsoriginin____.（）A.IGMPB.EGPC.ICMPD.BGP27．Thewell-knownpingprogramsendsan(a)____type8code0messagetothespecifiedhost.Thedestinationhostsseeingtheechorequest,sendbackatype0code0ICMPechoreply.（）A.ICMPB.IGMPC.TCPD.UDP28．Tracer-outisimplementedwith____messages.（）A.IGMPB.TCPC.UDPD.ICMP29．ThestandardTracer-outprogramactuallysendssetsof____packetswiththesameTTL.（）A.oneB.twoC.threeD.four30．IPv6increasesthesizeoftheIPaddressfrom32bitto____bit.（）A.64B.128C.256D.51231．HowmanybytesarethereinheaderofIPv6?（）A.8B.20C.40D.3232．IPv6doesnotallowforfragmentationandreassemblyatinter-media____.（）A.routersB.switchesC.endsystemD.hubs33．Fromsendertoreceivers,allpacketswilltakethesamepath,thisisweusea____service.（）A.datagramB.VCC.circuitD.Ethernet34．____meansmovingpacketsfromrouter’sinputporttoappropriaterouteroutputport?（）A.forwardingB.filteringC.routingD.switching35．____meansdeterminingroutetakenbypacketsfromsourcetodestination?（）A.forwardingB.filteringC.routingD.switching36．Arouterworksin____layer?（）A.NetworkingB.DatalinkC.ApplicationD.Physical37．Aswitchworksin____layer?（）A.NetworkingB.DatalinkC.ApplicationD.Physical38．Networkinglayerprovidesservicesbetweentwo____.（）A.HostsB.ProcessesC.ApplicationsD.Machines39．Linklayerprovidesservicesbetweentwo____.（）A.HostsB.ProcessesC.ApplicationsD.Machines40．Theinternet’snetworklayerprovidesasingleservice----thatis____.（）A.ReliabledatatransferB.FlowcontrolC.CongestioncontrolD.Best-effort-service41．Datagramnetworkprovidesnetwork-layer____.（）A.connectionlessserviceB.connectionserviceC.bothofaboveD.neitherofAandB42．VCnetworkprovidesnetwork-layer____.（）A.connectionlessserviceB.connectionserviceC.bothofaboveD.neitherofAandB43．InVCnetwork,eachpacketcarries____.（）A.VCidentifierB.destinationhostaddressC.IPaddressD.Macaddress44．AVCconsistsofthreepart,thisthreepa