川大软院计网选择题答案Chapter1含答案.docx

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川大软院计网选择题答案Chapter1含答案.docx

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川大软院计网选择题答案Chapter1含答案.docx

川大软院计网选择题答案Chapter1含答案

A theformatofmessagesexchangedbetweentwoormorecommunicatingentities

B theorderofmessagesexchangedbetweentwoormorecommunicatingentities

C theactionstakenonthetransmissionofamessageorotherevent

D thetransmissionsignalsaredigitalsignalsoranalogsignals

Inthefollowingoptions,whichisdefinedinprotocol?

（ A ）

A theactionstakenonthetransmissionand/orreceiptofamessageorotherevent

B theobjectsexchangedbetweencommunicatingentities

C thecontentintheexchangedmessages

D thelocationofthehosts

Anapplicationcanrelyontheconnectiontodeliverallofitsdatawithouterrorandintheproperorder.Thesentencedescribes（C ）.

A flowcontrol

B congestion-control

C reliabledatatransfer

D connection-orientedservice

TheInternet’sconnection-orientedservicehasaname,itis（ A ）.

A TCP

B UDP

C TCP/IP

D IP

TheInternet’sconnectionlessserviceiscalled（ B ）.

A TCP

B UDP

C TCP/IP

D IP

Whichofthefollowingnodesbelongstothenetworkcore?

A.aWebServer B.aHostwithWin2003Server

C.aRouterwithNATservice D.aSupernodeonSkypeNetwork

IntheInternet,theequivalentconcepttoendsystemsis（）A.

A hosts

B servers

C clients

D routers

IntheInternet,endsystemsareconnectedtogetherby（ C ）.

A copperwire

B coaxialcable

C communicationlinks

D fiberoptics

EndsystemsaccesstotheInternetthroughits（C ）.

A modems

B protocols

C ISP

D sockets

Inthefollowingoptions,whichbelongstothenetworkcore?

（ B ）

A endsystems

B routers

C clients

D servers

Endsystems,packetswitches,andotherpiecesoftheInternet,run（ D ）thatcontrolthesendingandreceivingofinformationwithintheInternet.

A programs

B processes

C applications

D protocols

Theinternetallows（ D ）runningonitsendsystemstoexchangedatawitheachother.

A clientsapplications

B serverapplications

C P2Papplications

D distributedapplications

Theprotocolsofvariouslayersarecalled（ A ）.

A theprotocolstack

B TCP/IP

C ISP

D networkprotocol

IntheOSIreferencemodel,theupperlayersoftheOSImodelare,incorrectorderD

A Session,application,presentation

B Session,presentation,application

C Session,application,presentation,physical

D Application,presentation,session

ThelowerlayersoftheOSImodelare,incorrectorderD

A physical,system,network,logical

B physical,logical,network,system

C physical,transport,network,datalink

D physical,datalink,network,transport

TheInternetProtocol（IP）generallycorrespondstowhichOSIlayer?

A Network（layerthree）

B Transport（layerfour）

C Datalink（layertwo）

D Session（layerfive）

WhatlayeroftheOSImodelisdesignedtoperformerrordetectionfunctions?

A Physical

B Datalink

C Network

D transport

WhichofthefollowingprotocollayersisnotexplicitlypartoftheInternetProtocolStack?

_____B____

A.applicationlayer B.sessionlayer

C.datalinklayer D.transportlayer

The5-PDUiscalled__A_

A.message B.segment

C.datagram D.frame

TheInternet’snetworklayerisresponsibleformovingnetwork-layerpacketsknownasB（）fromonehosttoanother.

A frame

B datagram

C segment

D message

Transport-layerpacketsarecalled:

A.message B.segment C.datagram D.frame

Theunitsofdataexchangedbyalink-layerprotocolarecalled（ A）.

A Frames

B Segments

C Datagrams

D bitstreams

Therearetwofundamentalapproachestobuildinganetworkcore,（ B ）andpacketswitching.

A electricalcurrentswitching

B circuitswitching

C dataswitching

D messageswitching

Datagramnetworksandvirtual-circuitnetworksdifferinthat（ C ）.

A datagramnetworksarecircuit-switchednetworks,andvirtual-circuitnetworksarepacket-switchednetworks.

B datagramnetworksarepacket-switchednetworks,andvirtual-circuitnetworksarecircuit-switchednetworks.

C datagramnetworksusedestinationaddressesandvirtual-circuitnetworksuseVC.numberstoforwardpacketstowardtheirdestination.

D datagramnetworksuseVC.numbersandvirtual-circuitnetworksusedestinationaddressestoforwardpacketstowardtheirdestination.

（A ）meansthattheswitchmustreceivetheentirepacketbeforeitcanbegintotransmitthefirstbitofthepacketontotheoutboundlink.

A Store-and-forwardtransmission

B FDM

C End-to-endconnection

D TDM

In（ C ）networks,theresourcesneededalongapathtoprovideforcommunicationbetweentheendsystemarereservedforthedurationofthecommunicationsession.

A packet-switched

B data-switched

C circuit-switched

D message-switched

In（ A ）networks,theresourcesarenotreserved;asession’smessagesusetheresourcesondemand,andasaconsequence,mayhavetowaitforaccesstocommunicationlink.

A packet-switched

B data-switched

C circuit-switched

D message-switched

Inacircuit-switchednetwork,ifeachlinkhas n circuits,foreachlinkusedbytheend-to-endconnection,theconnectiongets（ A）ofthelink’sbandwidthforthedurationoftheconnection.

A afraction1/n

B all

C 1/2

D ntimes

For（C ）,thetransmissionrateofacircuitisequaltotheframeratemultipliedbythenumberofbitsinaslot.

A CDMA

B packet-switchednetwork

C TDM

D FDM

Thenetworkthatforwardspacketsaccordingtohostdestinationaddressesiscalled（ D）network.

A circuit-switched

B packet-switched

C virtual-circuit

D datagram

Thenetworkthatforwardspacketsaccordingtovirtual-circuitnumbersiscalled（ C ）network.

A circuit-switched

B packet-switched

C virtual-circuit

D datagram

Thetimerequiredtopropagatefromthebeginningofthelinktothenextrouteris（ C）.

A queuingdelay

B processingdelay

C propagationdelay

D transmissiondelay

Processingdelaydoesnotincludethetimeto（B ）.

A examinethepacket’sheader

B waittotransmitthepacketontothelink

C determinewheretodirectthepacket

D checkbit-errorinthepacket

Inthefollowingfourdescriptions,whichoneiscorrect?

（ C）

A Thetrafficintensitymustbegreaterthan1.

B Thefractionoflostpacketsincreasesasthetrafficintensitydecreases.

C Ifthetrafficintensityisclosetozero,theaveragequeuingdelaywillbeclosetozero.

D Ifthetrafficintensityisclosetoone,theaveragequeuingdelaywillbeclosetoone.

Suppose, a istheaveragerateatwhichpacketsarriveatthequeue, R isthetransmissionrate,andallpacketsconsistof L bits,thenthetrafficintensityis（ B ）,

A LR／a

B La／R

C Ra／L

D LR／a

Supposethereisexactlyonepacketswitchbetweenasendinghostandareceivinghost.Thetransmissionratesbetweenthesendinghostandtheswitchandbetweentheswitchandthereceivinghostare R1 and R2,respectively.Assumingthattheswitchusesstore-and-forwardpacketswitching,whatisthetotalend-to-enddelaytosendapacketoflength L?

（Ignorequeuingdelay,propagationdelay,andprocessingdelay.）（ A ）

A L/R1＋L/R2

B L/R1

C L/R2

D noneoftheabove

Wearesendinga30MbitMP3filefromasourcehosttoadestinationhost.Supposethereisonlyonelinkbetweensourceanddestinationandthelinkhasatransmissionrateof10Mbps.Assumethatthepropagationspeedis2*108 meters/sec,andthedistancebetweensourceanddestinationis10,000km.Alsosupposethatmessageswitchingisused,withthemessageconsistingoftheentireMP3file.Howmanybitswillthesourcehavetransmittedwhenthefirstbitarrivesatthedestination?

A.1bit B.30,000,000bits C.500,000bits D.noneoftheabove

Inthefollowingentries,whichisnotakindofaccessnetwork?

（D ）

A residentialaccess

B companyaccess

C wirelessaccess

D localaccess

Thefollowingtechnologiesmaybeusedforresidentialaccess,exceptD

A.HFC

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