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1．Theinformationtobecommunicatedinadatacommunicationssystemisthe_______.A、MediumB、ProtocolC、TransmissionD、MessageD2．Communicationbetweenacomputerandakeyboardinvolves______________transmission.A、simplexB、half-duplexC、full-duplexD、automaticA3._______referstothestructureorformatofthedata,meaningtheorderinwhichtheyarepresented.A、SemanticsB、TimingC、SyntaxD、noneoftheaboveC4.Thehost-to-hostdeliveryoftheentiremessageistheresponsibilityofthe_______layer.A、NetworkB、TransportC、ApplicationD、PhysicalA5.InOSI/RM,the_______layerliebetweenthetransportlayerandtheapplicationlayer.A、datalinkandnetworkB、sessionandpresentationC、sessionandnetworkD、presentationandnetworkB6.WhendataaretransmittedfromdeviceAtodeviceB,theheaderfromA'slayer4isreadbyB's_______layer.A、PhysicalB、DatalinkC、TransportD、NoneoftheaboveC7.WhywastheOSImodeldeveloped?A、ManufacturersdislikedtheTCP/IPprotocolsuite.B、TherateofdatatransferwasincreasingexponentiallyC、StandardswereneededtoallowanytwosystemstocommunicateD、NoneoftheaboveC8.IntheOSImodel,encryptionanddecryptionarefunctionsofthe________layer.A、transportB、presentationC、sessionD、applicationB9._______isaprocess-to-processprotocolthataddsonlyportaddresses,checksumerrorcontrol,andlengthinformationtothedatafromtheupperlayer.A、TCPB、UDPC、IPD、NoneoftheaboveB10.Thephysical,datalink,andnetworklayersarethe______supportlayers.A、userB、networkC、both(a)and(b)D、noneoftheaboveA11.The_________productdefinesthenumberofbitsthatcanfillthelink.A、bandwidth-periodB、frequency-amplitudeC、bandwidth-delayD、delay-amplitudeC12._______encodinghasatransitionatthebeginningofeach0bit.A、RZB、ManchesterC、DifferentialManchesterD、NoneoftheaboveC13.Ifthebaudrateis400foraQPSKsignal,thebitrateis________bps.A、100B、400C、800D、1600C14.In_____transmission,thefrequencyofthecarriersignalismodulatedtofollowthechangingvoltagelevel(amplitude)ofthemodulatingsignal.Thepeakamplitudeandphaseofthecarriersignalremainconstant,butastheamplitudeoftheinformationsignalchanges,thefrequencyofthecarrierchangescorrespondingly.A、AMB、PMC、FMD、noneoftheaboveC15.______canbeappliedwhenthebandwidthofalink(inhertz)isgreaterthanthecombinedbandwidthsofthesignalstobetransmitted.A、TDMB、FDMC、Both(a)or(b)D、Neither(a)or(b)B16.A________networkismadeofasetofswitchesconnectedbyphysicallinks,inwhicheachlinkisdividedintonchannels.A、line-switchedB、frame-switchedC、circuit-switchedD、noneoftheaboveC17.In__________,eachpacketistreatedindependentlyofallothers.A、datagramswitchingB、circuitswitchingC、frameswitchingD、noneoftheaboveA18.The_______addressintheheaderofapacketinadatagramnetworknormallyremainsthesameduringtheentirejourneyofthepacket.A、sourceB、destinationC、localD、noneoftheaboveB19．Incyclicredundancychecking,thedivisoris_______theCRC.A、ThesamesizeasB、onebitlessthanC、onebitmorethanD、NoneoftheaboveC20．Weaddrredundantbitstoeachblocktomakethelengthn=k+r.Theresultingn-bitblocksarecalled_________.A、datawordsB、codewordsC、blockwordsD、noneoftheaboveB21．Toguaranteecorrectionofupto5errorsinallcases,theminimumHammingdistanceinablockcodemustbe________.A.5B、6C、11D、noneoftheaboveC22．InaGo-Back-NARQ,ifthewindowsizeis63,whatistherangeofsequencenumbers?A.0to63B、0to64C、1to63D、1to64A23．InGo-Back-NARQ,ifframes4,5,and6arereceivedsuccessfully,thereceivermaysendanACK_______tothesender.A、5B、6C、7D、noneoftheaboveC24．In________framing,weneedadelimiter(flag)todefinetheboundaryoftwoframes.A、fixed-sizeB、variable-sizeC、standardD、noneoftheaboveB25．In_________protocols,weuse________.A、character-oriented;bytestuffingB、character-oriented;bitstuffingC、bit-oriented;characterstuffingD、noneoftheaboveA26．_______controlreferstoasetofproceduresusedtorestricttheamountofdatathatthesendercansendbeforewaitingforacknowledgment.A、FlowB、ErrorC、TransmissionD、NoneoftheaboveA27．The_______Protocolhasbothflowcontrolanderrorcontrol.A、Stop-and-WaitB、Go-Back-NARQC、Selective-RepeatARQD、both(b)and(c)D28．TheStop-And-WaitARQ,Go-Back-NARQ,andtheSelectiveRepeatARQarefor______channels.A、noisyB、noiselessC、either(a)or(b)D、neither(a)nor(b)A29．InGo-Back-NARQ,if5isthenumberofbitsforthesequencenumber,thenthemaximumsizeofthesendwindowmustbe_____A、15B、16C、31D、1C30．ThevulnerabletimeforCSMAisthe________propagationtime.A、thesameasB、twotimesC、threetimesD、NoneoftheaboveA31．Inthe_______method,afterthestationfindsthelineidleitsendsorrefrainfromsendingbasedontheoutcomeofarandomnumbergenerator.Ifthelineisbusy,ittriesagain.A、non-persistentB、1-persistentC、p-persistentD、NoneoftheaboveC32．In___________methods,nostationissuperiortoanotherstationandnoneisassignedthecontroloveranother.A、randomaccessB、controlledaccessC、channelizationD、noneoftheaboveA33．In________,astationmonitorsthemediumafteritsendsaframetoseeifthetransmissionwassuccessful.Ifso,thestationisfinished.If,however,thereisacollision,theframeissentagain.A、CSMA/CAB、CSMA/CDC、either(a)or(b)D、both(a)and(b)B34．IfanEthernetdestinationaddressis07:01:02:03:04:05,thenthisisa______address.A、unicastB、multicastC、broadcastD、anyoftheaboveB35．WhichofthefollowingcouldnotbeanEthernetmulticastdestination?A、77:7B:6C:DE:10:00B、9B:AA:C1:23