搜索
诚信应考,考试作弊将带来严重后果！华南理工大学期末考试《ComputerNetworks》A试卷注意事项：1.考前请将密封线内填写清楚；2.所有答案请直接答在试卷上(注：选择题答案请填入题目前面的表格中)；3．考试形式：闭卷；4.本试卷共五大题，满分100分,考试时间120分钟。题号12345总分得分评卷人1.Selectthecorrectchoice.(30scores,everyoneis2scores)NO.123456789101112131415solution(1)ItisthearchitectureforTCP/IPprotocolstack,whichonebelowdoesn’tbelongtotheapplicationlayer(B)?A.TELNETB.ICMPC.POPD.SMTP(2)WhydoHTTP,FTP,SMTPandPOP3runontopofTCPratherthanUDP?(A)A.ReliabledatatransferB.ThroughputC.Real-timeD.Security(3)SupposeHostAwantstosendafiletoHostB,therearethreelinksbetweenAtoB,andtheratesofthethreelinksarerespectivelyR1=2Mbps,R2=1Mbps,andR3=4Mbps.Ifnoanyothertrafficinthenetwork,whatisthethroughputforthefiletransfer?(B)A.2MbpsB.1MbpsC.4MbpsD.7Mbps(4)Supposeanapplicationgenerateschunksof120bytesofdataeverysecond,andeachchunkgetsencapsulatedinaTCPsegmentandthenanIPdatagram(nooptionsfields).Whatpercentageofeachdatagramwillcontainapplicationdata?(B)A.80%B.75%C.60%D.25%(5)Thejobofdeliveringthedatainatransport-layersegmenttothecorrectsocketiscalled(A)._____________________…姓名学号学院专业座位号(密封线内不答题)……………………………………………………密………………………………………………封………………………………………线……………………………………线………………………………………A.DemultiplexingB.MultiplexingC.TDMD.FDM(6)Considersendinga999bytedatagramintoalinkthathasanMTUof500bytes,(B)A.2fragmentsarecreatedwithoffsetfieldvalue0,500,respectivelyB.3fragmentsarecreatedwithoffsetfieldvalue0,480,960,respectivelyC.3fragmentsarecreatedwithoffsetfieldvalue0,60,120,respectivelyD.Noneoftheseabove(7)Abouttheencapsulationrelationshipsofsegment、datagramandframe,whichofthefollowingiscorrect?(C)A.Segmentisencapsulatedwithintheframe,andtheframeisencapsulatedwithinthedatagram.B.DatagramisencapsulatedwithintheSegment,andtheSegmentisencapsulatedwithintheframe.C.Segmentisencapsulatedwithinthedatagram,andthedatagramisencapsulatedwithintheframe.D.Frameisencapsulatedwithinthedatagram,andthedatagramisencapsulatedwithinthesegment.(8)TCPhaswhichofthefollowingcharacteristics:(D)A.FlowcontrolB.ConnectionestablishmentC.CongestioncontrolD.Alloftheabove(9)WhatistheICMPusedfor？(C)A.ErrorreportingB.UsedbypingC.AandBD.Noneabove.(10)Ataking-turnsMACprotocolhaswhichofthefollowingcharacteristics:(B)A.thereisnosinglepointfailureB.itdoesnotgeneratecollisionsC.thereisnomasternodeD.alloftheabove(11)IntheEthernettwo-layerswitches,howistheforwardingtableestablished?(B)A.ManualconfigurationB.Self-learningC.RoutingalgorithmD.Destinationaddresslearning(12)Whicharetheerrordetectionandcorrectiontechniquesusedofteninlinklayer?(A)A.CRCB.ChecksumC.ParitychecksD.Noneoftheabove(13)InroutingamongASs,whichofthefollowingissuesdominants?(A)A.RoutingPolicyB.GeographicaldistancebetweenAssC.CurrentcongestionlevelsintheASsD.NumberofASstraversed(14)AnARPquerypacketisencapsulatedin(B)A.alink-layerframeaddressedtoaspecificadapterB.alink-layerbroadcastframeC.anIPdatagramD.noneoftheabove(15)TwoimportantreasonsthattheInternetisorganizedasahierarchyofnetworksforthepurposesofroutingare(C)A.LeastcostandmaximumfreecircuitavailabilityB.MessagecomplexityandspeedofconvergenceC.ScaleandadministrativeautonomyD.Linkcostchangesandlinkfailure2.Filltheblank.(10scores,everyblankis1score)(1)Thetaskofthedatalinklayerisprovidingdatatransmissionservicesbetween_________Adjacentnodes__________;Thetaskofthenetworklayerisprovidingdatatransmissionservicesbetween_______hosts___________;andthetaskoftransportlayerisprovidingdatatransmissionservicesbetween________processes___________.(2)Thetwokeyfunctionsofnetworklayerare_______Forwarding________and________routing__________.(3)TworoutingprotocolshavebeenusedextensivelyforroutingwithinanautonomoussystemintheInternet:RIPprotocoland__OSPF____protocol.(4)TheheaderofIPdatagramhasa_____TTL______field,whenthevalueofthefieldis0,thedatagramtransmittedwillbediscarded.(5)RIPadvertisementstypicallyannouncethenumberofhopstovariousdestination;BGPupdates,ontheotherhand,announcethe________SequenceofASsontheroutes___________tothevariousdestinations.(6)TCPprovidesa________Flowcontrol________servicetoitsapplicationtoeliminatethepossibilityofthesenderoverwhelmingthereceiver.(7)Thetool(command)thatcanbeusedtodeterminethenumberofhopstoadestinationandtheroundtriptime(RTT)foreachhopis______Traceroute________.3.Judgethefollowingquestionsastrueorfalse.(10scores,everyoneis1scores)(1)WhenauserrequestaWebpagethatconsistsofsometextandtwoimages.Forthispage,theclientwillsendonerequestmessageandreceivethreeresponsemessage.(2)Withawindowsizeof1,SR,GBN,andthealternatingbitprotocolarefunctionallyequivalent.(3)Whenusingdistancevectorroutealgorithm,thecompletenetworktopologyinformationmustbeknownbyarouter.(4)InaP2Pfile-sharingapplication,thereisnonotionofclientandserversidesofacommunicationsession.(5)AllnodesconnectedtotheInternetmustimplementUDP.(6)MediaAccessControlisafunctionofthedata-linklayer.(7)Emailsaredeliveredtoreceiver'sserverusingPOP3protocol.(8)BothCIDRandNATcanleadtomuchmoreefficientuseoftheavailableIPv4addressspace.(9)CollisionswillnotoccurunderCSMA/CDMACprotocol.(10)WhenaTCPsegmentarrivestoahost,thesockettowhichthesegmen