計算機網(wǎng)絡英文題庫附chapter

Chapter1ComputerNetworksandtheInternet

1．The( )isaworldwidecomputernetwork,that

is,anetworkthatinterconnectsmillionsof

computingdevicesthroughouttheworld.ppt3

ApublicInternet

BIntranet

Cswitchnet

Dtelevisionnet

2．Whichkindofmediaisnotaguidedmedia?( )

twisted-paircopperwire

acoaxialcable

fiberoptics

digitalsatellitechannel

3．Whichkindofmediaisaguidedmedia?( )

geostationarysatellite

low-altitudesatellite

fiberoptics

wirelessLAN

4．Theunitsofdataexchangedbyalink-layer

protocolarecalled( ).

Frames

Segments

Datagrams

bitstreams

5．Whichofthefollowingoptionbelongstothecircuit-switchednetworks?( )

FDM

TDM

VCnetworks

bothAandB

6．( )makessurethatneithersideofaconnectionoverwhelmstheothersidebysendingtoomanypacketstoofast.

Reliabledatatransfer

Flowcontrol

Congestioncontrol

Handshakingprocedure

7．( )meansthattheswitchmustreceivetheentire

packetbeforeitcanbegintotransmitthefirst

bitofthepacketontotheoutboundlink.

Store-and-forwardtransmission

FDM

End-to-endconnection

TDM

8．Datagramnetworksandvirtual-circuitnetworksdifferinthat( ).

datagramnetworksarecircuit-switchednetworks,andvirtual-circuitnetworksarepacket-switchednetworks.

datagramnetworksarepacket-switchednetworks,andvirtual-circuitnetworksarecircuit-switchednetworks.

datagramnetworksusedestinationaddressesandvirtual-circuitnetworksuseVC.numberstoforwardpacketstowardtheirdestination.

datagramnetworksuseVC.numbersandvirtual-circuitnetworksusedestinationaddressestoforwardpacketstowardtheir

destination.

9．Inthefollowingoptions,whichoneisnotaguided

media?( )

twisted-pairwire

fiberoptics

coaxialcable

satellite

10．Processingdelaydoesnotincludethetimeto

( ).

Aexaminethepacket’sheader

Bwaittotransmitthepacketontothelink

determinewheretodirectthepacket

checkbit-errorinthepacket

11．Inthefollowingfourdescriptions,whichoneiscorrect?( )

A

Thetraffic

intensity

mustbegreater

than

1.

B

Thefraction

oflost

packets

increasesas

thetrafficintensitydecreases.

C

If

the

traffic

intensity

is

close

to

zero,

theaveragequeuingdelaywillbecloseto

zero.

D

If

the

traffic

intensity

is

closeto

one,

theaveragequeuingdelaywillbecloseto

one.

12．TheInternet

’snetworklayer

isresponsible

for

movingnetwork-layer

packets

knownas(

)

from

onehosttoanother.

frame

datagram

segment

message

13．Theprotocolsofvariouslayersarecalled( ).

theprotocolstack

TCP/IP

ISP

networkprotocol

14．Therearetwoclassesofpacket-switchednetworks:( )networksandvirtual-circuitnetworks.

datagram

circuit-switched

television

telephone

15．Accessnetworkscanbelooselyclassifiedintothreecategories:residentialaccess,companyaccessand( )access.

cabled

wireless

campus

cityarea

Question16～17

Suppose,aistheaveragerateatwhichpackets

arriveatthequeue,Risthetransmissionrate,and

allpacketsconsistofLbits,thenthetraffic

intensityis(16),anditshouldnogreaterthan

(17).

16．ALR／a

La／R

Ra／L

LR／a

17．A2

1C0

D-1

18．IntheInternet,theequivalentconcepttoendsystemsis( ).

hosts

servers

clients

routers

19．IntheInternet,endsystemsareconnected

togetherby( ).

copperwire

coaxialcable

communicationlinks

fiberoptics

20．EndsystemsaccesstotheInternetthroughits

( ).

modems

protocols

ISP

sockets

21．Endsystems,packetswitches,andotherpieces

oftheInternet,run( )thatcontrolthe

sendingandreceivingofinformationwithinthe

Internet.

Aprograms

Bprocesses

Capplications

Dprotocols

22．Therearemanyprivatenetworks,suchasmanycorporateandgovernmentnetworks,whosehostscannotexchangemessageswithhostsoutsideof

theprivatenetwork.Theseprivatenetworksareoftenreferredtoas( ).

internets

LAN

intranets

WAN

23．Theinternetallows( )runningonitsendsystemstoexchangedatawitheachother.

clientsapplications

serverapplications

P2Papplications

distributedapplications

24．TheInternetprovidestwoservicestoitsdistributedapplications:aconnectionlessunreliableserviceand( )service.

flowcontrol

connection-orientedreliable

congestioncontrol

TCP

25．Itdefinestheformatandtheorderofmessages

exchangedbetweentwoormorecommunicatingentities,aswellastheactionstakenonthetransmissionand/orreceiptofamessageorotherevent.Thesentencedescribes( ).

Internet

protocol

intranet

network

26．Inthefollowingoptions,whichdoesnotdefineinprotocol?( )

theformatofmessagesexchangedbetweentwoormorecommunicatingentities

theorderofmessagesexchangedbetweentwoormorecommunicatingentities

theactionstakenonthetransmissionof

amessageorotherevent

Dthetransmissionsignalsaredigital

signalsoranalogsignals

27．Inthefollowingoptions,whichisdefinedin

protocol?( )

Atheactionstakenonthetransmissionand/or

receiptofamessageorotherevent

Btheobjectsexchangedbetween

communicatingentities

thecontentintheexchangedmessages

thelocationofthehosts

28．Inthefollowingoptions,whichdoesnotbelong

tothenetworkedge?( )

endsystems

routers

clients

servers

29．Inthefollowingoptions,whichbelongstothenetworkcore?( )

endsystems

routers

clients

servers

30．Inthefollowingoptions,whichisnotthe

bundledwiththeInternet’s

connection-orientedservice?( )

reliabledatatransfer

guaranteeofthetransmissiontime

flowcontrol

Dcongestion-control

31．Anapplicationcanrelyontheconnectionto

deliverallofitsdatawithouterrorandintheproperorder.Thesentencedescribes( ).

flowcontrol

congestion-control

reliabledatatransfer

connection-orientedservice

32．Itmakessurethatneithersideofaconnectionoverwhelmstheothersidebysendingtoomanypacketstoofast.Thesentencedescribes( ).

flowcontrol

congestion-control

connection-orientedservice

reliabledatatransfer

33．IthelpspreventtheInternetfromenteringa

stateofgridlock.Whenapacketswitchbecomescongested,itsbufferscanoverflowandpacket

losscanoccur.Thesentencedescribes( ).

Aflowcontrol

Bcongestion-control

Cconnection-orientedservice

Dreliabledatatransfer

34．TheInternet’sconnection-orientedservicehas

aname,itis( ).

ATCP

BUDP

CTCP/IP

DIP

35．Inthefollowingoptions,whichservicedoesnotbeprovidedtoanapplicationbyTCP?( )

reliabletransport

flowcontrol

videoconferencing

congestioncontrol

36．TheInternet’sconnectionlessserviceiscalled( ).

TCP

UDP

TCP/IP

IP

37．Inthefollowingoptions,whichdoesnotuseTCP?( )

ASMTP

internettelephone

FTP

HTTP

38．Inthefollowingoptions,whichdoesnotuseUDP?( )

Internetphone

videoconferencing

streamingmultimedia

telnet

39．Therearetwofundamentalapproachestobuildinganetworkcore,( )andpacketswitching.

electricalcurrentswitching

circuitswitching

dataswitching

messageswitching

40．In( )networks,theresourcesneededalongapathtoprovideforcommunicationbetweenthe

endsystemarereservedforthedurationofthecommunicationsession.

packet-switched

data-switched

circuit-switched

message-switched

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

packet-switched

data-switched

circuit-switched

message-switched

42．Inacircuit-switchednetwork,ifeachlinkhas

ncircuits,foreachlinkusedbytheend-to-end

connection,theconnectiongets( )ofthe

link’sbandwidthforthedurationofthe

connection.

Aafraction1/n

Ball

C1/2

Dntimes

43．For( ),thetransmissionrateofacircuitis

equaltotheframeratemultipliedbythenumber

ofbitsinaslot.

ACDMA

packet-switchednetwork

TDM

FDM

44．( )meansthattheswitchmustreceivetheentirepacketbeforeitcanbegintotransmitthefirstbitofthepacketontotheoutboundlink.

Queuingdelay

Store-and-forwardtransmission

Packetloss

Propagation

45．Thenetworkthatforwardspacketsaccordingtohostdestinationaddressesiscalled( )network.

circuit-switched

packet-switched

virtual-circuit

datagram

46．Thenetworkthatforwardspacketsaccordingto

virtual-circuitnumbersiscalled( )network.

Acircuit-switched

Bpacket-switched

Cvirtual-circuit

Ddatagram

47．Inthefollowingentries,whichisnotakind

ofaccessnetwork?( )

Aresidentialaccess

Bcompanyaccess

Cwirelessaccess

Dlocalaccess

48．Supposethereisexactlyonepacketswitch

betweenasending

hostandareceiving

host.

The

transmission

rates

betweenthe

sending

host

and

theswitchandbetweentheswitchandthe

receivinghostare

R1andR2,respectively.

Assumingthat

the

switchusesstore-and-forward

packetswitching,whatisthetotalend-to-end

delaytosendapacketoflength

?(Ignore

L

queuingdelay,propagationdelay,and

processingdelay.)(

)

L/R1＋L/R2

L/R1

L/R2

noneoftheabove

49．Thetimerequiredtoexaminethepacket’sheader

anddeterminewheretodirectthepacketispart

ofthe( ).

queuingdelay

processingdelay

propagationdelay

transmissiondelay

50．Thetimerequiredtopropagatefromthebegin