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-1-注意：1.可以用英文答题，也可以用中文答题。2.答案请写在每种类型题目的答题区中！！！一MultipleChoice(20points,2pointseachproblem)1、OSPFroutingprotocoltypicallyrunsover:A.IPB.TCPC.UDPD.noneoftheabove2、ThetransferofanWebdocumentfromonehosttoanotheris:A.loss-intolerantandtimeinsensitiveB.loss-tolerantandtimesensitiveC.loss-intolerantandtimesensitiveD.noneoftheabove3、Considersendinga999bytedatagramintoalinkthathasanMTUof500bytes.A.2fragmentsarecreatedwithoffsetfieldvalue0,500,respectivelyB.3fragmentsarecreatedwithoffsetfieldvalue0,480,960,respectivelyC.3fragmentsarecreatedwithoffsetfieldvalue0,60,120,respectivelyD.Noneoftheabove4、Supposeanapplicationgenerateschunksof120bytesofdataeverysecond,andeachchunkgetsencapsulatedinaTCPsegmentandthenanIPdatagram(nooptionsfields).Whatpercentageofeachdatagramwillcontainapplicationdata?A.80%B.75%C.60%D.25%5、Wearesendinga30MbitMP3filefromasourcehosttoadestinationhost.Supposethereisonlyonelinkbetweensourceanddestinationandthelinkhasatransmissionrateof10Mbps.Assumethatthepropagationspeedis2*108meters/sec,andthedistancebetweensourceanddestinationis10,000km.Alsosupposethatmessageswitchingisused,withthemessageconsistingoftheentireMP3file.Howmanybitswillthesourcehavetransmittedwhenthefirstbitarrivesatthedestination?A.1bitB.30,000,000bitsC.500,000bitsD.noneoftheabove6、InroutingamongASs,whichofthefollowingissuesdominantsA.PolicyB.geographicaldistancebetweenASsC.currentcongestionlevelsintheASsD.numberofASstraversed7、AnARPquerypacketisencapsulatedinA.alink-layerframeaddressedtoaspecificadapterB.alink-layerbroadcastframe-2-C.anIPdatagramD.noneoftheabove8、Ataking-turnsprotocolhaswhichofthefollowingcharacteristicsA.thereisnosinglepointfailure.B.itdoesnotgeneratecollisionsC.thereisnomasternodeD.alloftheabove9、TCPhaswhichofthefollowingcharacteristics:A.flowcontrolB.connectionestablishmentC.congestioncontrolD.alloftheabove10、Whichofthefollowingstatementsistrue?A.Anetworkadapter(NIC)isanautonomousunit.B.Inadistance-vectorroutingalgorithm,eachnodehasamapoftheentirenetworkanddeterminestheshortestpathfromitselftoallothernodesinthenetwork.C.Anadapter’sMACaddresshasaflatstructureanddoesn’tchangenomatterwheretheadaptergoes.D.noneoftheabove二FillintheBlanks(24points,2pointseachproblem)1、Asapackettravelsfromonenodetothesubsequentnodealongthepath,thepacketsuffersfromseveraltypesofdelaysateachnodealongthepath.Themostimportantofthesedelaysarethe_______delay,_______delay,_________delay,and_______delay.2、TheInternetmailsystemhasthreemajorcomponents:_________,_________________,and______________________.3、_______________________________________iscalledtransport-layermultiplexinganddemultiplexing.4、Computernetworksthat__________________________arecalledvirtual-circuitnetworks;Computernetworksthat___________________arecalleddatagramnetworks.5、Thereare4componentsinrouter’sarchitecture.Theyareinputports,________,outputportsand_________.And______connectstherouter’sinputportstoitsoutputports;_______executestheroutingprotocols.6、Historically,tworoutingprotocolshavebeenusedextensivelyforroutingwithinanautonomoussystemintheInternet:RIPprotocoland________protocol.And______isadistance-vectorprotocol.And_______isalink-stateprotocol.7、TCPprovidesa_______servicetoitsapplicationstoeliminatethepossibilityofthesenderoverwhelmingthereceiver..-3-8、Wecanclassifyjustaboutanymultipleaccessprotocolasbelongingtooneofthreecategories.CSMA/CDbelongsto________protocol.Pollingbelongsto________protocol.9、Ahubisa_____-layerdevice,andswitchesare_____-layerdevices.10、Cookietechnologyhasfourcomponents:acookieheaderlineinHTTPresponsemessage;acookieheaderlineintheHTTPrequestmessage;_____________________________;__________________.11、Twobasicapproachestowardpipelinederrorrecoverycanbeidentified:_______________and____________.Andin_______protocol,thereceiverdiscardsout-of-order-packets..12、Therearetwofundamentalapproachestobuildinganetworkcore:_____switchingand_____switching.Andin____switchednetworks,theresourcesarenotreserved;asession’smessagesusetheresourcesondemand,andasaconsequence,mayhavetowaitforaccesstoacommunicationlink.三TrueorFalse(10points,1pointeachproblem)1、WhenauserrequestaWebpagethatconsistsofsometextandtwoimages.Forthispage,theclientwillsendonerequestmessageandreceivethreeresponsemessages.2、Itispossibleforamailclienttosende-mailmessagesoverHTTPratherthanSMTP.3、InTCP,theacknowledgementnumberthatahostputsinasegmentisthesequencenumberofthenextbytethehostisexpectingfromthesender.4、TCPappliesfastretransmittoasegmentwhenitestimatesunusuallylargeRTT.5、LocalDNSnameserverscacheresourcerecords,butdiscardthemafteraperiodoftimethatisontheorderofafewdays.6、FortheWebapplication,theuseragentistheuser’skeyboard.7、SupposethathostAwantstosenddataoverTCPtohostB,andhostBwantstosenddatatohostAoverTCP.TwoseparateTCPconnections-oneforeachdirection-areneeded.8、WhenaTCPsegmentarrivestoahost,thesockettowhichthesegmentisdirecteddependsonthesourceIPaddressofthedatagramencapsulatedthesegment，thesourceportnumber，thedestinationportnumberandthedestinationIPaddress.9、Thestop-and-waitprotocolishighlyin