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页数:8页
时间:2020-07-16
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1、1.Whichoffollowingcorrectlydescribetheroutera.packetswitchingb.collisionpreventiononaLANsegmentc.packetfilteringd.broadcastdomainenlargemente.broadcastfowrodingf.internetworkcommunication2.whichofthefollowingcorrectlydescriblestheroleofthedeviceinawancdg?a.adigitallocalloopb.arouterisc
2、ommonlyconsideredadcedevicec.amodemterminatesananlonglocalloopd.arouteriscommonlyconsideredadtedevicee.amodemterminatesadigitallocalloopf..acsu/dsuterminateananlonglocalloopg.amodemisusedtoterminateaT1simultaneous同时p14---3p16---1p19---62009.4.15.。。做到第21页第九题ThecorporateheadofficeofTestK
3、inghasateleconferencingsystemthatusesVOIP(voiceoverIP)technology.ThissystemusesUDPasthetransportforthedatatransmissions.IftheseUDPdatagramsarriveattheirdestinationoutofsequence,whatwillhappen?A.UDPwillsendanICMPInformationRequesttothesourcehost.B.UDPwillpasstheinformationinthedatagrams
4、uptothenextOSIlayerintheorderthattheyarrive.C.UDPwilldropthedatagrams.D.UDPwillusethesequencenumbersinthedatagramheaderstoreassemblethedatainthecorrectorder.E.UDPwillnotacknowledgethedatagramsandwaitforaretransmissionofthedatagrams.Answer:BExplanation:VOIPsystemsutilizeUDPbecauseitisfa
5、steranduseslessoverhead.Inaddition,thereliabletransportmechanismusedinTCPisuselesstoVOIPbecauseifapacketgetsdroppedandneedstoberesent,itwillbealreadytoolate.UDPprovidesaserviceforapplicationstoexchangemessages.UnlikeTCP,UDPisconnectionlessandprovidesnoreliability,nowindowing,andnoreord
6、eringofthereceiveddata.However,UDPprovidessomefunctionsofTCP,suchasdatatransfer,segmentation,andmultiplexingusingportnumbers,anditdoessowithfewerbytesofoverheadandwithlessprocessingrequired.UDPdatatransferdiffersfromTCPdatatransferinthatnoreorderingorrecoveryisaccomplished.Applications
7、thatuseUDParetolerantoflostdata,ortheyhavesomeapplicationmechanismtorecoverdataloss.P41---2p43-----3p50---7p53---1p60====6P63---9p74----3p76---4(e选项)p79---2p80---3p82----5路由器交换机的指示灯情况很重要。。。是欠缺。。。P86---1P86---2P88—4(未作)P91---3p94—6(线缆知识要看一下)P95---2P98----4(关于IEEE标准的记忆)P100---7(全双工半双工的
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