2021思科认证考试试题及答案5篇

2021思科认证考试试题及答案5篇第1篇

IGP是内部网关协议，BGP是外部网关协议。

此题为判断题(对，错)。

正确答案：V

在Cisco路由器上串行线路的默认的二层封装协议是()。

A.CHAP

B.HDLC

C.PPP

D.SLIP

正确答案：B

HDLC是一种面向()的链路层协议。

A.字符

B.比特

C.信兀

D.数据包

正确答案：B

Whichoneofthefollowingcharacteristicsistrueregardingtheuseofhubs

andswitches?

A.HubscanhavetheirportsbeconfiguredwithVLANs

B.Usinghubsiscostlywithregardtobandwidthavailability.

C.Switchescannotforwardbroadcasts.

D.Switchesaremoreefficientthanhubsinprocessingframes.

E.Switchesincreasethenumberofcollisiondomainsinthenetwork.

正确答案：E

解析：

Explanation:Switchesincreasesthenumberofcollisionsdomainsinthenetwork.Switch

esthatareconfiguredwithVLANswillreducethesizeofthecollisiondomainsbyincreasin

gthenumberofcollisiondomainsinanetwor^butmakingthemsmallerthanthatofoneb

igJIatnetwork.IncorrectAnswers^.SwitchesarecapableofVLANconfigurations^uth

ubsarenot.B.Hubsaregenerallytheleastcostlymethodpossibletoconnectmultipledev

icestogetherinanetwork.C.Switchesforwardbroadcastsandmulticast^bydefaulttoall

portswithinthesameVLAN.Onlyroutersblockallbroadcasttrafficbydefault.D.Switches

andhubscanbeequallyefficientinprocessingframesjntheory.Inpractice^witchesareg

enerallymoreefficientastheyusuallyhavemoreCPUandmemoryallocatedtothem^nd

aregenerallymuchmoreexpensivethanasimplehub.

WhiletroubleshootinganissueintheEzonexamLANyounoticethata

networkinterfaceporthascollisiondetectionandcarriersensingenabledona

sharedtwistedpairnetwork.Fromthisstatement,whatisknownaboutthe

networkinterfaceport?

A.ThisisanEthernetportoperatingathalfduplex

B.ThisisanEthernetportoperatingatfullduplex

C.ThisisaportonanetworkinterfacecardinaPC

D.Thisis10MB/sswitchport

E.Thisisa100MB/sswitchport

F.Noneoftheabove

正确答案：A

A

RIP路由在()时间内没有收到更新会标记为不可达路由()

A.90s

B.120S

C.180S

D.240S

正确答案：C

2021思科认证考试试题及答案5篇第2篇

HowcouldtheEzonexamcorporationbenefitfromusingVLANsontheir

network?

(Selectthreeanswerchoices.)

A.VLANsallowaccesstonetworkservicesbasedondepartment,not

physicallocation.

B.VLANsutilizepacketfilteringtoenhancenetworksecurity.

C.VLANsprovidealow-latency,highbandwidthinternetworkingalternative.

D.VLANsprovideamethodofcommunicationbetweenIPaddressesinlarge

networks.

E.VLANsestablishsegmentedbroadcastdomainsinswitchednetworks.

F.VLANscangreatlysimplifyadding,moving,orchanginghostsonthe

network.

正确答案：AEF

A,E,F解析：Explanation:

VLANsestablishbroadcastdomainsinswitchednetworks,sobyvirtueofhaving

theoptiontocreatemanyefficientbroadcastdomains,congestionisreduced

andnetworkthroughputisgreatlyenhanced.VLANsallownetworkstobe

dividedbydepartmentorresourceneeds,ratherthenbyphysicallocation.When

peoplemovedepartments,leaveadepartment,orjoinadepartment,

administrationiseasyandconvenientwithafewkeystrokes.

IncorrectAnswers:

B,D.Thesewouldberouterfunctionsatlayer3.SwitchesandVLANsoperateat

layer2oftheOSImodel.

C.TheuseofVLANsmayactuallyincreasethelatencyinsomecases,astraffic

fromoneVLANtotheotherwillneedtoberouted.

要启用LACP并将交换机端口加入端口信道L可使用下面哪两个命令之一?()

A.Switch(config)#interfaceport-channell

B.Switch(config)#channel-group1modeactive

C.Switch#interfaceport-channel1

D.Switch(config-if)#channel-group1modeactive

答案：AD

Whyisfull-duplexEthernetsuperiortoitssingle-duplexcounterpart?(Select

twoanswerchoices.)

A.Itusesinexpensivehubs

B.Itoperateswithoutcollisions

C.Itoperatesonswitches

D.Itprovidesfasterdatatransfer

E.Itutilizesfewerwiringpairs

正确答案：BD

解析：Explanation:

FullduplexEthernetallowsconcurrentsendingandreceiving,whichallowsthe

fullbandwidthtobeusedforbothsendingandreceiving.Theresultisacollision

freenetworkwithincreasedthroughput.

IncorrectAnswers:

A,C.Theseareincorrectbecausefullduplexdoesn'trequirehubsorswitches.Full

duplexoperationcanbeusedonswitchandrouterports,aswellasPChosts.

E.Thisisincorrectbecausefullduplexactuallyusesmorewiringpairs.Infull

duplex,bothwirepairsareused.Halfduplexusesonlyasinglepair.

关于静态NAT，下面()说法是正确的。

A.静态NAT转换在缺省情况下24小时后超时

B.静态NAT转换从地址池中分配

C.静态NAT将内部地址一对一静态映射到内部全局地址

D.CISCO路由器缺省使用了静态NAT

正确答案：C

CDPisbeingusedthroughouttheEzonexamnetwork.Whataretworeasons

whytheEzonexamnetworkadministratorwoulduseCDP?(Choosetwo)

A.Todeterminethestatusofnetworkservicesonaremotedevice

B.ToobtaintheIPAddressofaconnecteddeviceinordertotelnettothe

device

C.Toverifythetypeofcableinterconnectingtwodevices

D.ToverifyLayer2connectivitybetweentwodeviceswhenLayer3fails

E.ToobtainVLANinformationfromdirectlyconnectedswticehs

F.Todeterminethestatusoftheroutingprotocolsbetweendirectly

connectedrouters

G.Tosupportautomaticnetworkfailoverduringoutages

正确答案：BD

B,D

对于以下ACL语句描述正确的是()

RI(config)#ipaccess-liststandardTELNET

RI(config-stdFacl)#permit192.168.4.20.0.0.0

Rl(c^ifig)#lineyty04

Rl(config_1ine)#access-classTELNETin

A.只允许192.168.4.2的数据流穿过Rl

B只允许192.168.4.2对Rl进行TELNET

C.只允许192.168.4.2对Rl进行TELNET并拒绝其它流量

D.只允许192,168.4.0/24网段的数据流穿过R1

正确答案：B

2021思科认证考试试题及答案5篇第3篇

在大型网络中选择OSPF而不选择RIP的原因是()

A.更快的路由收敛

B.需要更少的路由器内存

C.需要更少的CPU的资源

D.更优的选路，路由无环路

正确答案：AD

下列哪些内部路由协议支持VLSM()

A.RIP-1

B.RIP-2

C.EIGRP

D.OSPF

E.IS-IS

正确答案：BCDE

Afterworkingonarouter,someproblemsariseandyouwishtoviewthe

commandsthatyourecentlyentered.WhichIOScommandopensthehistory

bufferanddisplaysthemostrecentlyenteredcommands?

A.Showhistory

B.Showbuffers

C.Showtypedcommands

D.Showterminalbuffer

E.Showcommand

F.Noneoftheabove

正确答案：A

A解析：Explanation:

Therouterwillbufferpreviouslyenteredcommands.Bydefault,the"show

history"commandwilldisplaytheprevioustencommandsthatwereentered.To

seethecontentsofthebufferyouentertheshowhistorycommand.

IncorrectAnswers:

B.Thiscommandwillshowthememorybufferinformation

C,D.Theseareinvalidcommands.

交换机工作在OSI七层模型的哪一层()

A.物理层

B.数据链路层

C.网络层

D.传输层

正确答案：B

Showcdpinterface命令是用于显示以下哪一项的（）

A.CDP的时间值和接口状态

B.邻居路由器的接口配置

C.邻居设备的IP地址

D.CDP保持时间

正确答案：A

扩展ACL和标准ACL的区别（）。

A.标准的ACL在禁止和允许方面比扩展的ACL更高的精度

B.扩展的ACL核查数据包的源地址和目标地址和端口号

C.他们都可以查端口号

D.他们都可以查特殊协议和其他参数

正确答案：B

2021思科认证考试试题及答案5篇第4篇

把访问权限表应用到路由器端口的命令是：（）

A.permitaccess-list101out

B.ipaccess-group101out

C.applyaccess-list101out

D.access-class101out

正确答案：B

OSI七层模型中，"段”是哪一层数据封装的名称（）

A.物理层

B.数据链路层

C.网络层

D.传输层

正确答案：D

下列对RIP的配置中，合法的命令是（）

A.routerrip100network10.12.0.0

B.routerrip100network10.0.0.0

C.routerripnetwork10.12.0.0

D.routerrip100network10.0.0.0

正确答案：C

ThecorporateheadofficeofEzonexamhasateleconferencingsystemthat

usesVOIP(voiceoverIP)technology.ThissystemusesUDPasthetransportfor

thedatatransmissions.IftheseUDPdatagramsarriveattheirdestinationoutof

sequence,whatwillhappen?

A.UDPwillsendanICMPInformationRequesttothesourcehost.

B.UDPwillpasstheinformationinthedatagramsuptothenextOSIlayer

intheorderthattheyarrive.

C.UDPwilldropthedatagrams.

D.UDPwillusethesequencenumbersinthedatagramheadersto

reassemblethedatainthecorrectorder.

E.UDPwillnotacknowledgethedatagramsandwaitforaretransmissionof

thedatagrams.

正确答案：B

解析：Explanation:

VOIPsystemsutilizeUDPbecauseitisfasteranduseslessoverhead.Inaddition,

thereliabletransportmechanismusedinTCPisuselesstoVOIPbecauseifa

packetgetsdroppedandneedstoberesent,itwillbealreadytoolate.

UDPprovidesaserviceforapplicationstoexchangemessages.UnlikeTCP,UDPis

connectionlessandprovidesnoreliability,nowindowing,andnoreorderingof

thereceiveddata.However,UDPprovidessomefunctionsofTCP,suchasdata

transfer,segmentation,andmultiplexingusingportnumbers,anditdoessowith

fewerbytesofoverheadandwithlessprocessingrequired.UDPdatatransfer

differsfromTCPdatatransferinthatnoreorderingorrecoveryisaccomplished.

ApplicationsthatuseUDParetolerantoflostdata,ortheyhavesomeapplication

mechanismtorecoverdataloss.

Youneedtodescribethevarioustypesofflowcontroltoyourco-workers.

Whichofthefollowingaretypesofflowcontrolthatcanbeusedinanetwork?

(Choosethree)

A.Congestionavoidance

B.Windowing

C.Cut-through

D.Buffering

E.LoadBalacing

F.FastForward

正确答案：ABD

A,B,D

请参见图示1040.0网络发生故障哪种机制可防止R2接收有关1040.0网络

的错误更新信息（）

10.1.0010.2.0.010.3.0.010.4.0.0

A.水平分割

B抑制计时器

C.路由毒化

D.触发更新

正确答案：A

2021思科认证考试试题及答案5篇第5篇

TYPE（类型）字段是思科在HDLC包头字段中额外添加的。

此题为判断题（对，错）。

正确答案：V

WhichofthefollowingatruestatementsregardingtheuseofVLANsto

segmentanetwork?(Selectthree)

A.Theyincreasethesizeofcollisiondomains

B.Theyallowlogicalgroupingofusersbyfunction.

C.Theycanenhancenetworksecurity.

D.Theyincreasethesizeofthebroadcastdomainwhiledecreasingthe

numberofcollisiondomains.

E.Theyincreasethenumberof