计算机网络教程自顶向下方法选择题及答案.docx
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计算机网络教程自顶向下方法选择题及答案
Chapter4NetworkLayer
1.
Packetizingatthenetworklayerinvolves
A）Encapsulatingthepayloadatthesource
B）Addsaheaderthatcontainsthesourceanddestinationinformation
C）Decapsulatingthepayloadatthedestination
D）Allofthechoicesarecorrect
2.
Routersinthepatharenotallowedto___________________________.
A）fragmentthepackettheyreceive
B）decapsulatethepacket
C）changesourceordestinationaddress
D）Allofthechoicesarecorrect
3.
ThenetworklayerintheInternetprovides_________________.
A）comprehensiveerrorandflowcontrol.
B）limitederrorcontrol,butnoflowcontrol.
C）comprehensiveerrorcontrolbutlimitedflowcontrol.
D）Allofthechoicesarecorrect
4.
Inavirtual-circuitapproach,theforwardingdecisionisbasedonthevalueofthe_____________fieldinthepacketheader.
A）sourceaddress
B）destinationaddress
C）label
D）Noneofthechoicesarecorrect
5.
Inadatagramapproach,theforwardingdecisionisbasedonthevalueofthe_____________fieldinthepacketheader.
A）sourceaddress
B）destinationaddress
C）label
D）Noneofthechoicesarecorrect
6.
Theperformanceofanetworkcanbemeasuredintermsof________.
A）delay
B）throughput
C）packetloss
D）allofthechoicesarecorrect
7.
Transmissiondelay（time）istheratioof______________________.
A）transmissionratetopacketlength
B）transmissionratetodistance
C）packetlengthtotransmissionrate
D）processingtimetotransmissionrate
8.
Propagationdelay（time）istheratioof______________________.
A）transmissionratetopropagationspeed
B）propagationspeedtodistance
C）packetlengthtopropagationspeed
D）distancetopropagationspeed
9.
Whentheloadinthenetworkreachesthenetworkcapacity,thepacketdelay___________andthenetworkthroughputreaches______________.
A）increasessharply;itsminimum
B）increasessharply;itsmaximum
C）decreasessharply;itsminimum
D）decreasessharply;itsmaximum
10.
Inopen-loopcongestioncontrol,policiesareapplied____________________.
A）topreventcongestionbeforeithappens
B）toalleviatecongestionafterithappens
C）toeitherpreventcongestionbeforeithappensortoalleviatecongestionafterithappens
D）Noneofthechoicesarecorrect
11.
The__________________techniqueisoneoftheopen-loopcongestionpolicy
A）backpressure
B）chokepacket
C）implicitsignaling
D）Noneofthechoicesarecorrect
12.
The__________________techniqueisoneoftheclose-loopcongestionpolicy
A）acknowledgmentpolicy
B）chokepacket
C）discardingpolicy
D）Noneofthechoicesarecorrect
13.
IPisa_________protocol.
A）connection-orientedunreliable
B）connection-orientedreliable
C）connectionlessunreliable
D）connectionlessreliable
14.
AnHLENvalueofdecimal10means_______.
A）thereare10bytesofoptions
B）thereare10bytesintheheader
C）thereare40bytesofoptions
D）thereare40bytesintheheader
15.
Ifthefragmentoffsethasavalueof100,itmeansthat_______.
A）thedatagramhasnotbeenfragmented
B）thedatagramis100bytesinsize
C）thefirstbyteofthedatagramisbyte800
D）Noneofthechoicesarecorrect
16.
Whatisneededtodeterminethenumberofthelastbyteofafragment?
A）offsetnumber
B）totallength
C）bothoffsetnumberandthetotallength
D）Noneofthechoicesarecorrect
17.
TheIPheadersizeis_______byteslong.
A）20to60
B）20
C）60
D）Noneofthechoicesarecorrect
18.
PacketsintheIPlayerarecalled_________.
A）segments
B）datagrams
C）frames
D）Noneofthechoicesarecorrect
19.
Thetotallengthfielddefinesthetotallengthofthedatagram_________.
A）includingtheheader
B）excludingtheheader
C）excludingtheoptionlength
D）Noneofthechoicesarecorrect
20.
Whenadatagramisencapsulatedinaframe,thetotalsizeofthedatagrammustbelessthanthe_______.
A）MUT
B）MAT
C）MTU
D）Noneofthechoicesarecorrect
21.
AnIPv4addressisnormallyrepresentedinbase____indotted-decimalnotation.
A）16
B）256
C）10
D）Noneofthechoicesarecorrect
22.
Inclassfuladdressing,theIPv4addressspaceisdividedinto_______classes.
A）3
B）4
C）5
D）Noneofthechoicesarecorrect
23.
Thenumberofaddressesassignedtoanorganizationinclasslessaddressing_______.
A）canbeanynumber
B）mustbeamultipleof256
C）mustbeapowerof2
D）Noneofthechoicesarecorrect
24.
Thefirstaddressassignedtoanorganizationinclasslessaddressing_______.
A）mustbeevenlydivisiblebythenumberofaddressesintheorganization
B）mustbedivisibleby128
C）mustbelongtooneoftheA,B,orCclasses
D）Noneofthechoicesarecorrect
25.
Insubnetting,thenumberofaddressesineachsubnetmust_______.
A）beapowerof2
B）beamultipleof128
C）bedivisibleby128
D）Noneofthechoicesarecorrect
26.
WhatisthedefaultprefixlengthforclassAinCIDRnotation?
A）9
B）8
C）16
D）Noneofthechoicesarecorrect
27.
WhatisthedefaultprefixlengthforclassBinCIDRnotation?
A）9
B）8
C）16
D）Noneofthechoicesarecorrect
28.
WhatisthedefaultprefixlengthforclassCinCIDRnotation?
A）24
B）8
C）16
D）Noneofthechoicesarecorrect
29.
DHCPisa（an）___________layerprotocol.
A）application
B）transport
C）network
D）data-link
30.
InDHCP,theclientuses________portandtheserveruses_________port.
A）anephemeral;awell-known
B）awell-known;awell-known
C）awell-known;anephemeral
D）Noneofthechoicesarecorrect
31.
DHCPusestheservicesof_______.
A）UDP
B）TCP
C）IP
D）Noneofthechoicesarecorrect
32.
_________allowsasitetouseasetofprivateaddressesforinternalcommunicationandasetofglobalInternetaddressesforcommunicationwiththerestoftheworld.
A）DHCP
B）NAT
C）IMCP
D）Noneofthechoicesarecorrect
33.
Theideaofaddressaggregationwasdesignedtoalleviatetheincreaseinroutingtableentrieswhenusing________addressing.
A）classful
B）classless
C）classfulorclassless
D）Noneofthechoicesarecorrect
34.
Theuseofhierarchyinroutingtablescan________thesizeoftheroutingtables.
A）reduce
B）increase
C）neitherreducenorincrease
D）Noneofthechoicesarecorrect
35.
ICMPisa（an）_________layerprotocol.
A）application-layerprotocolthathelpsTCP/IPatthenetworklayer
B）transport-layerprotocolthathelpsTCP/IPatthenetworklayer
C）network-layerprotocol.
D）data-linklayerprotocolthathelpsTCP/IPatthenetworklayer
36.
WhichofthefollowingistrueaboutICMPmessages?
A）AnICMPerrormessagemaybegeneratedforanICMPerrormessage.
B）AnICMPerrormessagemaybegeneratedforafragmenteddatagram.
C）AnICMPerrormessagemaybegeneratedforamulticastdatagram.
D）Noneofthechoicesarecorrect
37.
Routinginsideanautonomoussystemisreferredtoas________routing.
A）interdomain
B）intradomain
C）out-of-domain
D）Noneofthechoicesarecorrect
38.
Routingbetweenautonomoussystemsisreferredtoas______routing.
A）interdomainrouting
B）intradomainrouting
C）out-of-domain
D）Noneofthechoicesarecorrect
39.
In_______routing,theleastcostroutebetweenanytwonodesistheroutewiththeminimumdistance.
A）pathvector
B）distancevector
C）linkstate
D）Noneofthechoicesarecorrect
40.
In________,eachnodemaintainsavector（table）ofminimumdistancestoeverynode.
A）pathvector
B）distancevector
C）linkstate
D）Noneofthechoicesarecorrect
41.
Indistancevectorrouting,eachnodeperiodicallysharesitsroutingtablewith_________andwheneverthereisachange.
A）everyothernode
B）itsimmediateneighbors
C）oneneighbor
D）Noneofthechoicesarecorrect
42.
TheRoutingInformationProtocol（RIP）isanintradomainroutingbasedon_________routing.
A）distancevector
B）linkstate
C）pathvector
D）Noneofthechoicesarecorrect
43.
Themetricusedby_______isthehopcount.
A）OSPF
B）RIP
C）BGP
D）Noneofthechoicesarecorrect
44.
InRIP,the________timercontrolstheadvertisingofregularupdatemessages.
A）garbagecollection
B）expiration
C）periodic
D）Noneofthechoicesarecorrect
45.
InRIP,the________timerisusedtopurgeinvalidroutesfromthetable.
A）garbagecollection
B）expiration
C）periodic
D）Noneofthechoicesarecorrect
46.
InRIP,the________timercontrolsthevalidityoftheroute.
A）garbagecollection
B）expiration
C）periodic
D）Noneofthechoicesarecorrect
47.
RIPusestheservicesof_______.
A）TCP
B）UDP
C）IP
D）Noneofthechoicesarecorrect
48.
The_________routingusestheDijkstraalgorithmtobuildaroutingtable.
A）distancevector
B）linkstate
C）pathvector
D）Noneofthechoicesarecorrect
49.
TheOpenShortestPathFirst（OSPF）protocolisanintradomainroutingprotocolbasedon_______routing.
A）distancevector
B）linkstate
C）pathvector
D）Noneofthechoicesarecorrect
50.
The_______protocolallowstheadministratortoassignacost,calledthemetric,toeachroute.
A）OSPF
B）RIP
C）BGP
D）Noneofthechoicesarecorrect
51.
InOSPF,a________linkconnectstworouterswithoutanyotherhostorrouterinbetween.
A）point-to-point
B）transient
C）stub
D）Noneofthechoicesarecorrect
52.
InOSPF,a_______linkisanetworkwithseveralroutersattachedtoit.
A）point-to-point
B）transient
C）stub
D）Noneofthechoicesarecorrect
53.
InOSPF,a________linkisanetworkconnectedtoonlyonerouter.
A）point-to-point
B）transient
C）stub
D）Noneofthechoicesarecorrect
54.
InOSPF,a____
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