计算机网络题库chapter4

Chapter4TheNetworkLayer1．Whatisthenameofanetwork-layerpacket?（）messagesegmentdatagramframe2．Whatarethetwomostimportantnetwork-layerfunctionsinadatagramnetwork?（）forwarding&routingforwarding&filteringrouting&detectingrouting&checking3．Whenapacketarrivesatarouter’sinputlink,theroutermustmovethepackettotheappropriateoutputlink,thisactioniscalled____?（）Forwardingroutingcutthroughfiltering4．Thenetworklayermustdeterminethepathtakenbypacketsastheyflowfromasendertoareceiver.Thisactioniscalled____?（）Forwardingroutingcutthroughexamine5．Arouterforwardsapacketbyexaminingthevalueofafieldinthearrivingpacket’sheader,andthenusingthisvaluetoindexintotherouter’sforwardingtable,thisvalueis?（）destinationIPaddresssourceIPaddressdestinationMACaddresssourceMACaddress6．IPbelongsto____layer?（）transportnetworkdatalinkphysical7．Whichlayerprovideshost-to-hostservices?（）transportnetworkdatalinkphysical8．Whichlayerprovidesaconnectionservicecalledvirtual-circuitnetworksandaconnectionlessservicecalleddatagramnetworks?（）transportnetworkdatalinkphysical9．IPV4hasa___bitaddress?（）4816326410．MACaddressis____bits?（）4816326411．TheInternet’snetworklayerhasthreemajorcomponents,thefirstcomponentistheIPprotocol,thesecondcomponentistheroutingprotocol,thefinalcomponentis____?（）forwardingaddresstranslationcheckICMP12．HowmanybitsspecifytheIPprotocolversioninadatagram?（）1bit2bits4bits8bits13．MostIPV4datagramdonotcontainoptionfield,howmanybytesaheaderhasinatypicalIPdatagram?（）4bytes8bytes16bytes20bytes14．HowmanybitsusedinIPdatagramexpresstotallengthoftheIPdatagram?（）4bits8bits16bits20bits15．Data-gramsarerarelylargerthan____?（）1500bytes65535bytes500bytes1024bytes16．NewversionofIP----IPV6doesnotallowfragmentin____?（）RouterHostBothofaboveNoneofabove17．HowdoestheTTLchangedbyoneeachtimethedatagramisprocessedbyarouter?（）decreaseincreasenochangealways018．WhichlayerprotocolisindicatedbythevalueofprotocolfieldinIPdatagram?（）applicationtransportnetworkdatalink19．IPoptionisdroppedinthe____header.（）IPv6IPv4TCPUDP20．ThedatafieldinIPdatagramcancarrymanytypesofdataexcept____.（）TCPUDPICMPMAC21．ICMPisusedfor____?（）ReliabledatatransferErrorreportingFlowcontrolCongestioncontrol22．SupposeyoureceiveanIPdatagramfromonelinkandcheckyourforwardingtabletodeterminetheoutgoinglink,butthisoutgoinglinkhasanMTUthatissmallerthanthelengthofIPdatagram.Whichtechnologywillbeused?（）resenddiscardfragmentnone23．ThedesignerofIPv4decidedtoputthejobofdatagramreassemblyin____.（）routerswitchhubendsystem24．IPaddressingassignsanaddressto223.10.198.250/29,thenetworkaddressforthisnetworkis____.（）223.10.198.248223.10.198.250223.10.198.0223.10.0.025．Ifalldata-gramsarrivingattherouterfromWANhavethesamedestinationIPaddress,thenhowdoestherouterknowtheinternalhosttowhichitshouldforwardagivendatagram?Thetrickistouse____tableatrouter,andincludeportnumbersaswellasIPaddressinthetableentries.（）routingforwardingARPNATtranslation26．WhenrunningaTelnet,FTP,orHTTPsession,youmayhaveencounteredanerrormessagesuchas“Destinationnetworkun-reachable”,Thismessagehaditsoriginin____.（）IGMPEGPICMPBGP27．Thewell-knownpingprogramsendsan(a)____type8code0messagetothespecifiedhost.Thedestinationhostsseeingtheechorequest,sendbackatype0code0ICMPechoreply.（）ICMPIGMPTCPUDP28．Tracer-outisimplementedwith____messages.（）IGMPTCPUDPICMP29．ThestandardTracer-outprogramactuallysendssetsof____packetswiththesameTTL.（）onetwothreefour30．IPv6increasesthesizeoftheIPaddressfrom32bitto____bit.（）6412825651231．HowmanybytesarethereinheaderofIPv6?（）820403232．IPv6doesnotallowforfragmentationandreassemblyatinter-media____.（）routersswitchesendsystemhubs33．Fromsendertoreceivers,allpacketswilltakethesamepath,thisisweusea____service.（）datagramVCcircuitEthernet34．____meansmovingpacketsfromrouter’sinputporttoappropriaterouteroutputport?（）forwardingfilteringroutingswitching35．____meansdeterminingroutetakenbypacketsfromsourcetodestination?（）forwardingfilteringroutingswitching36．Arouterworksin____layer?（）NetworkingDatalinkApplicationPhysical37．Aswitchworksin____layer?（）NetworkingDatalinkApplicationPhysical38．Networkinglayerprovidesservicesbetweentwo____.（）HostsProcessesApplicationsMachines39．Linklayerprovidesservicesbetweentwo____.（）HostsProcessesApplicationsMachines40．Theinternet’snetworklayerprovidesasingleservice----thatis____.（）ReliabledatatransferFlowcontrolCongestioncontrolBest-effort-service41．Datagramnetworkprovidesnetwork-layer____.（）connectionlessserviceconnectionservicebothofaboveneitherofAandB42．VCnetworkprovidesnetwork-layer____.（）connectionlessserviceconnectionservicebothofaboveneitherofAandB43．InVCnetwork,eachpacketcarries____.（）VCidentifierdestinationhostaddressIPaddressMacaddress44．AVCconsistsofthreepart,thisthreepartsdonotinclude____.（）PathfromsourcetodestinationVCnumbers,onenumberforeachlinkalongpathEntriesinforwardingtablesinroutersalongpathDestinationaddressIn____networking,aseriesofpacketmayfollowdifferentpathsandmayarriveoutoforder?（）DatagramVCTCPNoneofabove46．Theinternetisa(an)____network?（）DatagramVCBothofaboveNoneofabove47．Thefourcomponentsofarouterdonotinclude____?（）InputandoutputportsSwitchfabricRoutingprocessorSwitchingprocessor48．Therearethreekindsofswitchfabricforarouternormally,thosethreeswitchfabricdonotincludes____?（）SwitchingviamemorySwitchingviaabusSwitchingviaanInterconnection-NetworkPacketswitching49．Whichofthefollowingprotocolisusedforerrorreporting?（）ICMPTCPIPUDP50．Whichofthefollowingisnotaroutingprotocol?（）TCPRIPOSPFBGP51．IPV4hasa___bitsaddress?（）32641612852．IPaddressisidentifierfor____.（）HostRouterinterfaceBothofaboveNoneofabove53．“233.1.1.0/24”,wherethe/24notation,sometimesknownasa____.（）SubnetmaskNetworkingaddressHostaddressNoneofabove54．Subnetswithan8-,____-,and24-bitsubnetaddresseswereknowasclassA,B,andCnetworksrespectively.（）910121655．IPV6hasa___bitsaddress?（）32641612856．____meansthatIPv6nodesalsohaveacompleteIPv4implementationaswell?（）DualstackTunnelingBridgeconnectionForwarding57．____meansthatIPv6carriedaspayloadinIPv4data-gramamongIPv4routers?（）DualstackTunnelingBridgeconnectionForwarding58．Typicallyahostisattacheddirectlytoonerouter,the____forthehost.（）DefaultrouterSourcerouterDestinationrouterCorerouter59．Thedefaultrouterofthesourcehostisknownas____.（）DefaultrouterSourcerouterDestinationrouterCorerouter60．Thedefaultrouterofthedestinationhostisknownas____.（）DefaultrouterSourcerouterDestinationrouterCorerouter61．Apathbetweenthesourceanddestinationthathasbeastcostisknownas____.（）LeastcostpathShortestpathLargestcostpathNoneofabove62．Thepathwiththesmallestnumberoflinksbetweenthesourceandthedestinationisknownas____.（）LeastcostpathShortestpathLargestcostpathNoneofabove63．WhichoffollowingaboutDVisnotcorrect?（）IterativeSynchronousDistributedSelf-terminating64．Whichofthefollowingisnotintra-ASroutingprotocol?（）RIPOSPFIGRPBGP65．RIPisakindof____algorithm.（）DVLSBothofaboveNeitherofAandB66．OSPFisakindof____algorithm.（）DVLSBothofaboveNeitherofAandB67．Therouterinnon-backboneareasandperformonlyintra-ASroutingisknownas____.（）InternalroutersAreaborderroutersBackboneroutersBoundaryrouters68．____“summarize”distancestonetsinownarea,advertisetootherAreaBorderrouters.（）InternalroutersAreaborderroutersBackboneroutersBoundaryrouters69．____runsOSPFroutinglimitedtobackbone.（）InternalroutersAreaborderroutersBackboneroutersBoundaryrouters70．____connecttootherAS’s.（）InternalroutersAreaborderroutersBackboneroutersBoundaryrouters71．Whichofthefollowingisaninter-autonomoussystemroutingprotocol?（）RIPOSPFIGRPBGP72．____meanssendingapackettoallothernodesinthenetwork.（）BroadcastMulticastAny-castUni-cast73．A____packetisdeliveredtoonlyasubsetofnetworknodes.（）BroadcastMulticastAny-castUni-cast74．Meansthattheswitchmustreceivetheentirepacketbeforeitcanbegintotransmitthefirstbitofthepacketontotheoutboundlink.（）store-and-forwardtransmissionFDMEnd-to-endconnectionTDM75．Datagramnetworksandvirtual-circuitnetworksdifferin____.（）Datagramnetworksarecircuit-switchednetworks,andvirtual-circuitnetworksarepacket-switchednetworks.Datagramnetworksarepacket-switchednetworks,andvirtual-circuitnetworksarecircuit-switchednetworks.Datagramnetworksusedestinationaddressesandvirtual-circuitnetworksuseVC.Numberstoforwardpacketstowardtheirdestination.DatagramnetworksuseVC.Numbersandvirtual-circuitnetworksusedestinationaddressestoforwardpacketstowardtheirdestination.76．TheInternet’snetworklayerisresponsibleformovingnetwork-layerpacketsknownas____fromonehosttoanother.（）framedatagramsegmentmessage77．Theprotocolsofvariouslayersarecalled____.（）theprotocolstackTCP/IPISPnetworkprotocol78．Thetwoimportantnetwork-layerfunctionsare____.（）multiplexingandde-multiplexingroutingandforwardinglookupandforwardingroutingandIPaddressing79．Thevirtualcircuitincludesthreeidentifiablephasesbut____.（）setupdatatransferforwardingVCnumbersteardown80．Therearesomewaystoaccomplishtheswitchingintherouter,whichoneisnotincluded?（）switchingviamemoryswitchingviaabusswitchingviahubswitchingviaaninterconnection81．Intherouter,thepacketqueuescanformat____.（）institutionalcacheswitchfabricinputportroutingprocessor82．InIPV4datagramheader,whichfieldistoensurethatdatagramdonotcirculateforeverinthenetwork?（）typeofservicetime-to-liveheaderchecksumversion83．SupposeoneIPdatagramof5,000bytes(20bytesofIPheader)anditmustbeforwardedtoalinkwithanMTUof1,500bytes,theoffsetandflagofthesecondfragmentinheaderare____.（）185,0185,1370,1370,084．GiventheIPaddress202.96.104.8/20,itssubnetaddressis____.（）202.96.104.0202.96.96.0202.96.104.255202.96.111.25585．Ifthesubnetmaskis255.255.240.0,thenhowmanybitsindicatethehostaddress?（）2024121686．Inthefollowingfourfields,whichisinIPV6headerbutnotinIPV4?（）sourceaddressdestinationaddressversionflowlabel87．Onehostisattacheddirectlytoonerouter,therouteris____.（）NATroutergatewayrouterfirst-hoprouterintervalrouter88．TheInternet’snetworklayerincludesthefollowingcomponentsbut____.（）IPprotocoltheInternetMessageControlProtocolRoutingProtocolChannelPartitioningProtocol89．Inthefollowingprotocols,whichoneisinter-ASroutingprotocol?（）RIPOSPFBGPICMP90．Inthefollowingfourdescriptionsaboutautonomoussystem,whichoneisnotcorrect?（）Anautonomoussystemisacollectionofroutersunderthesameadministrativeandtechnicalcontrol.Allroutersinanautonomoussystemrunthesameroutingprotocol.Theroutingalgorithmrunningwithinanautonomoussystemiscalledanintra-ASroutingprotocol.TheroutersthatconnectAS-stoeachotherarecalleddefaultrouter.91．IntheloopoftheDijkstra’salgorithm,fornodex,addytoN’,andupdatethecostofy’sneighborv,thenD(v)is____.（）c(x,v)min{D(v),D(x)+c(x,v)}min{D(v),D(y)+c(y,v)}c(y,v)92．ConsiderthedataDis01110010001,ifuseevenparitycheckingapproach,theparitybitis(),ifuseoddparitycheckingapproach,theparitybitis____.（）0,00,11,01,193．Theabilitytodeterminetheinterfacestowhichaframeshouldbedirected,andthendirectingtheframetothoseinterfacesis____.（）filteringforwardingself-learningoptimalrouting94．Giventhatcostsareassignedtovariousedgeinthegraphabstraction.Inthefollowingfourdescriptions,whichoneisnotcorrect?（）Theshortestpathisthepathwithsmallestnumberoflinksbetweenthesourceanddestination.Theleastcostpathisnotalwaystheshortestpath.Ifalledgeshavesamecost,theleastcostpathmustbetheshortestpath.Ifalledgeshavevariouscosts,theleastcostpathmustnotbetheshortestpath.95．GiventheIPaddress202.96.104.8/20,itsbroadcastaddressis____.（）202.96.104.0202.96.96.0202.96.104.255202.96.111.25596．Ifthesubnetmaskis255.240.0.0,thenhowmanybitsindicatethehostaddress?（）2012241697．InIPV6datagramheader,thefieldNext-headerisequivalenttothefield()inIPV4.（）upper-layerprotocoltime-to-liveheaderchecksumversion98．Foronehost,itssourcerouterisalsocalled____.（）NATroutergatewayrouterfirst-hoprouterintervalrouter99．Inthefollowingfourdescriptionsaboutlink-state(LS)algorithm,whichoneisnotcorrect?（）TheLSalgorithmmustbeawareofthecostofeachlinkinthenetwork.TheLSalgorithmisadecentralizedalgorithmTheLSalgorithmcomputestheleastcostpathbetweenasourceanddestinationusingcompleteglobalknowledgeaboutthenetworkThecalculationofLSalgorithmcanberunatonesiteormultiplesites100．IntheinitializationoftheDijkstra’salgorithm,fornodex,ifyisnotaneighborofx,thenD(y)is____.（）01∞c(x,y)101．InDValgorithm,whenonenodeupdatesitsdistancevector,itmust____.（）sendtheupdatedroutingtabletoitsneighborssendtheupdatedroutingtabletoallthenodesintheASsendtheupdatedroutingtableatrandomdonothing102．NowwehadknownIPaddressis211.197.3.158/26,Pleasecompute:(1).Networkaddress?(2).Broadcastaddress?(3).Howmanyhostsarethereinthenetwork?(4).FisthostIPaddress?(5).LasthostIPaddress?103．Forthegiventopologyofthenetwork,useDijstra’sshortestpathalgorithmtocomputetheshortestpathfromAtoallnetworknodes.GiveashortestpathtreeandnodeA’sroutingtable.1EABDCF12522153104．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.ABCDFE