网工英语10套练习题

第1页网工英语10套练习题ISDN,whichstandsforIntegratedServicesDigitalNetwork,isasystemofdigitalphoneconnections,whichhasbeenavailableforoveradecade.Thissystemallowsdatatobetransmittedsimultaneouslyacrosstheworldusing(1)digitalconnectivity.WithISDN,voiceanddataarecarriedbybearerchannelsoccupyingabandwithof(2)(bitspersecond).SomeswitcheslimitBchannelstocapacityof56Kbps.Adatachannel(3)handlessignalingat16Kbpsor64Kbps,dependingon(4).Notethat,inISDNterminology,”k”means(5),andnot1024(2^10)asinmanycomputerapplications;therefore,a64Kbpschannelcarriesdataatarateof64000bps.Anewsetofstandardprefixeshasrecentlybeencreatedtohandlethis.Underthisscheme,”K”(Kilo)means1000(10^3),”M”(Mega)means1000000(10^6),andsoon,and“Ki”(Kibi)means1024(2^10),”Mi”(Mebi)means1048576(2^20).andsoon。(1).A.Multi-endsB.circleC.indirectD.end-to-end(2).A.34KbpsB.84KbpsC.64KbpsD.54Kbps(3).A.DchannelB.AchannelC.BchannelD.Cchannel(4).A.themethodB.thenumberC.theservicetypeD.theusertype(5).A.100000(10^5)B.1000(10^3)C.10000(10^4)D.100(10^2)答案:1:D,2:C,3:A,4:C,5:BBluetoothisauniversalradiointerfaceinthe(1)frequencyband第2页thatenablesportablecelectronicdevices(2)connectandcommunicate(3)viashortrange,adhocnetworks.Eachunitcansimultaneouslycommunicatewithupto(4)otherunitsperpiconet.Moreover,eachunitcansimultaneously(5)toseveralpiconets,BluetoothtechnologywhichapartfromEricsson,hasgainedthesupportofNokia,IBM,Toshiba,Intelandmanyothermanufactures,eliminatestheneedforwires,cablesandconnectorsforandbetweencordlessormobilephones,modems,headsets,PDAs,Computes,printers,progjectors,localaresnetworks,andsoon,andpavesthewayfornewandcompletelydifferentdevicesandapplications.(1).A.2.45GHzB.4.45GHzC.2.95GHzD.3.45GHz(2).A.inB.onC.toD.with(3).A.narrowlyB.wirelesslyC.freelyD.widely(4).A.useB.severC.hostD.base(5).A.relateB.addC.closeD.belong答案:1:A,2:C,3:B,4:B,5:D(1)isusedtoensuretheconfidentiality,integrityandauthenticityofthetwoendpointsintheprivatenetwork.the(2),anapplicationlayerprotocol,authenticateseachpeerinanIPsectransaction,IKEnegotiatessecuritypolicy,determiningwhichalgorithmmaybeusedtosetuptheRunnel.Italsohandlestheexchangofsessionkeysusedforthatonetransaction.Networksthatuse(3)tosecuredatatrafficcanautomaticallyauthenticatedevicesbyusing(4)第3页whichVerifytheidentitiesofthetwouserswhoaresendinginformationbackandforth.IPseccanbeidealwaytosecuredatainlargenetworksthatrequire(5)connectionsamongmanydevices。(1)A.EncryptionB.CodeC.CertificateD.Tunnel(2)A.associatedlinksB.InternetKeyExchangeCIPsecD.encryption(3)AauthenticityB.passwordC.IPsecD.InternetKeyExchange(4)A.protocolsB.keywordsC.IKED.digitalcertificates(5)A.freeB.strictC.secureD.remote答案:1:A,2:B,3:C,4:D,5:CLAPBisa(1)protocolthatprovidescompletedatatransparencyina(2)operation.Itsupportsapeer-to-peerlinkinthatneitherendofthelinkplaystheroleofthepermanentmasterstation.HDLCLAPBisthe(3)thatisusuallyusedby(4),the(5)standardforPacketSwitchedNetworks.(1)A．bit-orientedsynchronousB．byte-orientedsynchronousC．bit-orientedasynchronousD．byte-orientedasynchronous(2)A．half-duplexpoint-to-pointB．half-duplexpoint-to-pointsC．full-duplexpoint-to-pointD．full-duplexpoint-to-points(3)A．PhysicalLayerB．LinkLayerC．NetworkLayerD．TransportLayer(4)A．X.21B．X.25C．X.28D．X.29(5)A．ITUB．IEEEC．OSID．ANSI答案:1:A,2:C,3:B,4:B,5:ADatacommunicationsequipment(DEC)(1)theserialdatastreamfromtheDTEandconvertsittosomeformof(2)suitableoftransmissiononvoicegradelines.Atthe(3),theDCEperformsthereversefunctionofconveringthereceivedanalogsignaltoserialdigitaldatastream.ThesimplestformofDCEisa(4)ordataset.Atthetransmitend,themodemcanbeconsideredaformof(5),while第4页atthereceiveend,itcanbeconsideredaformofanalogtodigitalconverter.Themostcommonformsofmodulationbymodemsarefrequencyshiftkeying(FSK),phaseshiftkeying(PSK),andquadratureamplitudemodulation(QAM).IfthecablesandsignallevelsusedtointerconnecttheDTEandDCEwereleftunregulated,thevariationsgeneratedwouldprobablybeproporationtothenumberofmanufactures.ElectronicsIndustriesAssociation(EIA),anorganizationofmanufactuuersconcernedwithestablishingindustrystandards,haveagreedontheRS-232CasthestandardinterfacebetweentheDTEandthemodem.Thisisa25pincablepinshavedesignatedfuntonsandspecifiedsignallevels.(1)A.acceptsB.sendsC.deliversD.receives(2)A.digitalsignalB.analogsignalC.lightsignalD.soundsignal(3)A.backendB.frontendC.sendingendD.receiveend(4)A.modemB.cpuC.demodulatorD.modulator.(5)A.hostcomputerB.digitaltoanalogconverterC.analogtodigitalconverterD.secondaries答案:1:A,2:B,3:D,4:A,5:BInATM,cellsserveasuniversalunitsforallinformationtypes:data,voice,video,etc,Sinceswitchesknowbeforehandthesizeandformatofeachinformationunitsentthroughthenetwork,switcharchitecturescanbe(1),Futhermore,sincetheCMSdeterminestheconnectionpathduringconnectionsetup,switchesdonothavetomakecomplexroutingdecisionsona(2)basis.Communiciationpathscanbe第5页“hardwired”intotheswitch’scircuitstoenablefast,simpledecisions.Hardwaretechniques,usingVLSIbasedstatemachinesand,inthefuture,opticalswitchingtechniques,canbeappliedtoswitches.HardwareBasedswitchmatricestakeadvantageofallthese