精心整理Chapter1ComputerNetworksandtheInternet1．The()isaworldwidecomputernetwork,thatis,anetworkthatinterconnectsmillionsofcomputingdevicesthroughouttheworld.ppt3A publicInternetB IntranetC switchnetD televisionnet2．Whichkindofmediaisnotaguidedmedia?()A twisted-paircopperwireB acoaxialcableC fiberopticsD digitalsatellitechannel3．Whichkindofmediaisaguidedmedia?()A geostationarysatelliteB low-altitudesatelliteC fiberopticsD wirelessLAN4．ed().A FramesB SegmentsC DatagramsD bitstreams5．ABCD6．()makessurethatneithersideofaconnectionoverwhelmstheothersidebysendingtoomanypacketstoofast.A ReliabledatatransferB FlowcontrolC CongestioncontrolD Handshakingprocedure7．()meansthattheswitchmustreceivetheentirepacketbeforeitcanbegintotransmitthefirstbitofthepacketontotheoutboundlink.A Store-and-forwardtransmissionB FDMC End-to-endconnectionD TDM8．Datagramnetworksandvirtual-circuitnetworksdifferinthat().Adatagramnetworksarecircuit-switchednetworks,andvirtual-circuitnetworksarepacket-switchednetworks.Bdatagramnetworksarepacket-switchednetworks,andvirtual-circuitnetworksarecircuit-switchednetworks.D satellite10．Processingdelaydoesnotincludethetimeto().A examinethepacket’sheaderB waittotransmitthepacketontothelinkC determinewheretodirectthepacketD checkbit-errorinthepacket11．Inthefollowingfourdescriptions,whichoneiscorrect?()A Thetrafficintensitymustbegreaterthan1.BThefractionoflostpacketsincreasesasthetrafficintensitydecreases.CIfthetrafficintensityisclosetozero,theaveragequeuingdelaywillbeclosetozero.DIfthetrafficintensityisclosetoone,theaveragequeuingdelaywillbeclosetoone.12．TheInternet’snetworklayerisresponsibleformovingnetwork-layerpacketsknownas()fromonehosttoanother.A frameB datagramC segmentD message13．Theprotocolsofvariouslayersarecalled().A theprotocolstackB TCP/IPC ISPD networkprotocol14．Therearetwoclassesofpacket-switchednetworks:()networksandvirtual-circuitnetworks.A datagramB circuit-switchedC televisionD telephone15．Accessnetworkscanbelooselyclassifiedintothreecategories:residentialaccess,companyaccessand()access.A cabledB wirelessC campusD cityareaQuestion16～17Suppose,a istheaveragerateatwhichpacketsarriveatthequeue,Rhan(17).16． A LR／aB LaC RaD LR17．A 2B 1C 0D -118．IntheInternet,theequivalentconcepttoendsystemsis().A hostsB serversC clientsD routers19．IntheInternet,endsystemsareconnectedtogetherby().A copperwireB coaxialcableC communicationlinksD fiberoptics20．EndsystemsaccesstotheInternetthroughits().A modemsB protocolsC ISPD sockets21．Endsystems,packetswitches,andotherpiecesoftheInternet,run()thatcontrolthesendingandreceivingofinformationwithintheInternet.A programsB processesC applicationsD protocols22．Therearemanyprivatenetworks,suchasmanycorporateandgovernmentnetworks,whosehostscannotexchangemessage24．TheInternetprovidestwoservicestoitsdistributedapplications:aconnectionlessunreliableserviceand()service.A flowcontrolB connection-orientedreliableC congestioncontrolD TCP25．Itdefinestheformatandtheorderofmessagesexchangedbetweentwoormorecommunicatingentities,aswellastheactionstakenonthetransmissionand/orreceiptofamessageorotherevent.Thesentencedescribes().A InternetB protocolC intranetD network26．Inthefollowingoptions,whichdoesnotdefineinprotocol?()AtheformatofmessagesexchangedbetweentwoormorecommunicatingentitiesBtheorderofmessagesexchangedbetweentwoormorecommunicatingentitiesCtheactionstakenonthetransmissionofamessageorothereventDthetransmissionsignalsaredigitalsignalsoranalogsignals27．Inthefollowingoptions,whichisdefinedinprotocol?()Atheactionstakenonthetransmissionand/orreceiptofamessageorothereventB theobjectsexchangedbetweencommunicatingentitiesC thecontentintheexchangedmessagesD thelocationofthehosts28．Inthefollowingoptions,whichdoesnotbelongtothenetworkedge?()A endsystemsB routersC clientsD servers29．Inthefollowingoptions,whichbelongstothenetworkcore?()A endsystemsB routersC clientsD servers30．nternet’A reliabledatatransferBCD31．A flowcontrolB congestion-controlC reliabledatatransferD connection-orientedservice32．Itmakessurethatneithersideofaconnectionoverwhelmstheothersidebysendingtoomanypacketstoofast.Thesentencedescribes().A flowcontrolB congestion-controlC connection-orientedserviceD reliabledatatransfer33．IthelpspreventtheInternetfromenteringastateofgridlock.Whenapacketswitchbecomescongested,itsbufferscanoverflowandpacketlosscanoccur.Thesentencedescribes().A flowcontrolB congestion-controlC connection-orientedserviceD reliabledatatransfer34．TheInternet’sconnection-orientedservicehasaname,itis().A TCPB UDPC TCP/IPD IPA SMTPB internettelephoneC FTPD HTTP38．Inthefollowingoptions,whichdoesnotuseUDP?()A InternetphoneB videoconferencingC streamingmultimediaD telnet39．Therearetwofundamentalapproachestobuildinganetworkcore,()andpacketswitching.A electricalcurrentswitchingB circuitswitchingC dataswitchingD messageswitching40．In()networks,theresourcesneededalongapathtoprovideforcommunicationbetweentheendsystemarereservedforthedurationofthecommunicationsession.A packet-switchedB data-switchedC circuit-switchedD message-switched41．In()networks,theresourcesarenotreserved;asession’smessagesusetheresourcesondemand,andasaconsequence,mayhavetowaitforaccesstocommunicationlink.A packet-switchedB data-switchedC circuit-switchedD message-switched42．Inacircuit-switchednetwork,ifeachlinkhas n circuits,foreachlinkusedbytheend-to-endconnection,theconnectiongets()ofthelink’sbandwidthforthedurationoftheconnection.A afraction1/nB allC 1/2D ntimes43．For(),thetransmissionrateofacircuitisequaltotheframeratemultipliedbythenumberofbitsinaslot.A CDMAB packet-switchednetworkC TDMD FDM44．()meansthattheswitchmustreceivetheentirepacketbefoeoutboundlink.A QueuingdelayBC PacketlossD Propagation45．ABCD46．Thenetworkthatforwardspacketsaccordingtovirtual-circuitnumbersiscalled()network.A circuit-switchedB packet-switchedC virtual-circuitD datagram47．Inthefollowingentries,whichisnotakindofaccessnetwork?()A residentialaccessB companyaccessC wirelessaccessD localaccess48．Supposethereisexactlyonepacketswitchbetweenasendinghostandareceivinghost.Thetransmissionratesbetweenthesendinghostandtheswitchandbetweentheswitchandthereceivinghostare R1and R2,respectively.Assumingthattheswitchusesstore-and-forwardpacketswitching,whatisthetotalend-to-enddelaytosendapacketoflength L?(Ignorequeuingdelay,propagationdelay,andprocessingdelay.)()A L/R1＋L/R2B L/R1C L/R2D noneoftheabove51．Considersendingapacketof3000bitsoverapathof5links.Eachlinktransmitsat1000bps.Queuingdelays,propagationdelayandprocessingdelayarenegligible.(6points)(1).Supposethenetworkisapacket-switchedvirtualcircuitnetwork.VCsetuptimeis0.1seconds.Supposethesendinglayersaddatotalof500bitsofheadertoeachpacket.Howlongdoesittaketosendthefilefromsourcetodestination?(2).Supposethenetworkisapacket-switcheddatagramnetworkandaconnectionlessserviceisused.Nowsupposeeachpackethas200bitsofheader.Howlongdoesittaketosendthefile?(3).Supposethatthenetworkisacircuit-switchednetwork.Furthersupposethatthetransmissionrateofthecircuitbetweensourceanddestinationis200bps.Assuming0.02ssetuptimeand200bitsofheaderappendedtothepacket,howlongdoesittaketosendthepacket?Solution:?(1).?t=5*(3000+500)/1000+0.1=17.6s???(2).?t=5*(3000+200)/1000=16s???(3).?t=(3000+200)/200+0.02=16.02s??/:。