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1/6311105040计算机网络(A闭)2015-2016-1一、单项选择题(本大题共20小题,每小题1.5分,共30分)。提示:在每小题列出的四个备选项中只有一个是符合题目要求的,请将其代码填写在下表中。错选、多选或未选均无分。1.Whichofthefollowingprotocolsisanapplicationprotocol?_________A.CSMA/CDB.ICMPC.OSPFD.IMAP2.Whichofthefollowingprovidesreliablecommunication?_________A.IPB.TCPC.UDPD.alloftheabove3.Whichofthefollowingphysicalmediabelongstounguidedmedia?_________A.Twisted-PairCopperWireB.CoaxialCableC.FiberOpticsD.RadioChannels4.WhatistheuseofPingcommand?_________A.totestadeviceonthenetworkisreachableB.totestaharddiskfaultC.totestabuginapplicationD.togetthepathfromthesourcetodestination5.AuserrequestsaWebpagethatconsistsofsometextand3images.Thebrowser’scacheisempty.Forthispage,theclient’sbrowser:_________A.sends1httprequestmessageandreceives1httpresponsemessages.B.sends1httprequestmessageandreceives4httpresponsemessages.C.sends4httprequestmessageandreceives4httpresponsemessages.D.sends2httprequestmessageandreceives4httpresponsemessages.6.Thebroadcastaddressofnetwork102.105.64.0/23is_________A.102.105.64.255B.102.105.65.255C.102.105.255.255D.102.105.64.07.TheInternetisanexampleof_________A.cellswitchednetworkB.circuitswitchednetworkC.packetswitchednetworkD.alloftheabove8.ThedestinationIPaddressinaDHCPdiscovermessageis___________.A.theIPaddressofDHCPclientB.theIPaddressofDHCPserverC.255.255.255.255D.0.0.0.09.WhentheTimetoLive(TTL)inanIPpacketreacheszeroandthedestinationhasnotbeenreached,anICMP_________errormessageissentbacktothesendingmachine.A.destination-unreachableB.time-exceededC.parameter-problemD.noneoftheabove.10.WhichofthefollowingnetworkisNOTanexampleofrandom-accessmediaaccessprotocols?___________.2/6311105040计算机网络(A闭)2015-2016-1A.EthernetB.Wi-FiC.ALOHAD.Blue-tooth11.WhatistheminimumheaderlengthofanIPv4packet?_______.A.16bytesB.10bytesC.20bytesD.32bytes12.Whenauserretrieveshisemailfrommailserver,whichoffollowingprotocolscan’tbeused?A.POP3B.HTTPC.SMTPD.IMAP13.WhichofthefollowingservicesCANNOTbeprovidedbythedatalinklayer?_________A.flowcontrolB.congestioncontrolC.errordetectionD.linkaccess14.AportnumberinUPDis______bitslong.A.8B.16C.32D.noneoftheabove15.The_________utilityallowsyoutoquerytheDNSdatabasefromanycomputeronthenetworkandfindthehostnameofadevicebyspecifyitsIPaddress,orviceversaA.ipconfigB.tracertC.nslookupD.netstat16.Whenauserneedstosendtheserversomeinformationusinghttp,therequestlinemethodis___.A.GETB.HEADC.SENDD.POST17.InTCP,thetimeoutintervalisafunctionof:A.estimatedRTTatthesenderB.MSSandtheoverheadofasegmentC.thesizeofbufferatthereceiverD.thesizeofsendingwindow18.SupposehostAsendshostBoneTCPsegmentwithsequencenumber418,acknowledgementnumber571,and24bytesofdata.Thenthesequencenumberintheacknowledgementtothissegmentis_________A.442B.418C.571D.59519.InanEthernetframe,thepreambleisresponsiblefor__________A.collisiondetectionB.errordetectionC.synchronizationofthereceiver’sclocktothesender’sclock.D.multiplexing/demultiplexing20.Let’sassumethereis16-bitpiecedata1011101110011001,The8-bitInternetchecksumforthisdatashouldbe_________A.01010100B.01010101C.10101011D.10101010二、判断并说明理由(本大题共10小题,每小题2分,共20分)。1.SwitchesdecrementtheTTLfieldintheIPheader.3/6311105040计算机网络(A闭)2015-2016-12.TCPconnectionestablishmentusesathree-wayhandshakesotheTCPsender,theTCPreceiverandthesender’sInternetServiceProvidercanallagreeonacommonsetofoptionstobeusedforthissession.3.Innetworking,“besteffort”servicemeansthesamethingas“reliable”service(asprovidedbyTCP,forexample),incontrastto“reasonableeffort”servicewheretherearenoguaranteesthatthedatawilleverreachthedestination.4.Ahalf-duplexlinkcancarrydatafromAlicetoBob,orfromBobtoAlice,butnotinbothdirectionsatthesametime.5.InIPdatagram,achecksumfieldinIPheaderisusedtoperformerrordetectionforthewholedatagram.6.Ethernetprovidesunreliable,connectionlessservice.7.Inadatagramnetwork(suchasIP),routerskeeptrackofconnectionsbetweenendsystems.8.Therootdomainnameserverisasinglepointoffailure.9.Withnonpersistentconnectionsbetweenbrowserandoriginserver,itispossibleforasingleTCPsegmenttocarrytwodistinctHTTPrequestmessages.10.ThesizeoftheTCPrwndneverchangesthroughoutthedurationoftheconnection.三、简答题(本大题共3小题,共8分)。1.WhatisthepurposeofARP,describehowitwork?(3points)2.Considersendingapacketfromasourcehosttoadestinationhostoverafixedroute.Listthedelaycomponentsintheend-to-enddelay.Whichofthesedelaysareconstantandwhicharevariable?(3points)3.WhyisitsaidthatFTPsendscontrolinformation“out-of-band”?(2points)四、计算及分析题(本大题共5小题,共42分)。1.(8points)Forthisproblem,assumethatAliceistransmittingdatafromtheSichuanUniversitytoBob’slabatMianyangcity,SichuanProvince,usingadedicatedpoint-to-pointlinkthatis100kilometerslongandprovidesadatarateof109bits/sec.A.Ifthelengthofeachpacketisexactly10,000bits,includingallframingoverhead,findthetransmissiontimeforasinglepacket.(1point)B.Findtheone-waypropagationdelayfromAlicetoBob,ifsignalstravelataspeedof24/6311105040计算机网络(A闭)2015-2016-1/3C≡2×108meters/sec.(1point)C.Whatisthemaximumthroughput,inpacketspersecond,thatAlicecansendtoBobusingthestop-and-waitprotocol,assumingBob’sacknowledgment
本文标题:311105040-计算机网络(A闭)
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