2021思科认证考试历年真题8卷

2021思科认证考试历年真题精选8卷第1卷

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

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

如果一个内部网络对外的出口只有一个，那么最好配置()

A.缺省路由

B.主机路由

C.动态路由

D.静态路由

正确答案：A

帧中继环境中，在物理端口上，建立子接口的命令是()

A.create

B.interface

C.encapsulation

D.ipaddress

正确答案：B

AEzonexamswitchisconfiguredwithallportsassignedtoVLAN2.In

addition,allportsareconfiguredasfull-duplexFastEthernet.Whatistheeffectof

addingswitchportstoanewVLANonthisswitch?

A.Theadditionswillcreatemorecollisionsdomains.

B.IPaddressutilizationwillbemoreefficient.

C.Morebandwidthwillberequiredthanwasneededpreviously.

D.Anadditionalbroadcastdomainwillbecreated.

E.Thepossibilitythatswitchingloopswilloccurwillincreasedramatically.

正确答案：D

解析:Explanation:

AVLANisagroupofhostswithacommonsetofrequirementsthat

communicateasiftheywereattachedtothesamewire,regardlessoftheir

physicallocation.AVLANhasthesameattributesasaphysicalLAN,butitallows

forendstationstobegroupedtogethereveniftheyarenotlocatedonthesame

LANsegment.

Networksthatusethecampus-wideorend-to-endVLANslogicallysegmenta

switchednetworkbasedonthefunctionsofanorganization,projectteams,or

applicationsratherthanonaphysicalorgeographicalbasis.Forexample,all

workstationsandserversusedbyaparticularworkgroupcanbeconnectedtothe

sameVLAN,regardlessoftheirphysicalnetworkconnectionsorinteractionwith

otherworkgroups.

Networkreconfigurationcanbedonethroughsoftwareinsteadofphysically

relocatingdevices.CiscorecommendstheuseoflocalorgeographicVLANsthat

segmentthenetworkbasedonIPsubnets.Eachwiringclosetswitchisonitsown

VLANorsubnetandtrafficbetweeneachswitchisroutedbytherouter.The

reasonsfortheDistributionLayer3switchandexamplesofalargernetwork

usingboththecampus-wideandlocalVLANmodelswillbediscussedlater.

AVLANcanbethoughtofasabroadcastdomainthatexistswithinadefinedset

ofswitches.PortsonaswitchcanbegroupedintoVLANsinordertolimit

unicast,multicast,andbroadcasttrafficflooding.Floodedtrafficoriginatingfrom

aparticularVLANisonlyfloodedoutportsbelongingtothatVLAN,including

trunkports,soaswitchthatconnectstoanotherswitchwillnormallyintroduce

anadditionalbroadcastdomain.

YouareasystemsadministratorandyouareabouttoassignstaticIP

addressestovariousserversonyournetwork.Forthenetwork4/29

therouterisassignedtothefirstusablehostaddress,whilethelastusablehost

addressgoestoyourSalesserver.Whichoneofthefollowingcommandswould

youenterintotheIPpropertiesboxofthesalesserver?

A.IPaddress:4SubnetMask:255,255.255.248Default

Gateway:192,168.20.9

B.IPaddress:54SubnetMask:255,255.255.0DefaultGateway:

C.IPaddress:192,168.20.30SubnetMask48DefaultGateway:

5

D.IPaddress:0SubnetMask40DefaultGateway:

7

E.IPaddress:192,168.20.30SubnetMask40DefaultGateway:

5

正确答案：C

解析：

ExplanationAsubnetmaskuses29bits.Thismeansthatituses5bitsinthe4thoctet.Thiseq

uatesto48.Thisnetworkhas3bitsforhosts.Usingthe2n-2formula(23-

2)inthiscase),weareleftwith6(2*2*2-

2=6)hostaddresses.l4isthenetworkaddress.Thereforethenextaddress(l

5)wouldbethefirsthostaddress.Thisaddressmustbeassignedtotherouter,

whichservesasthegatewayforthenetwork.Thelastavailablehostaddresswouldbel92.

168.20.30(4+6).Thisaddressisassignedtotheserver.Thebroadcastaddre

ssisl1.

2021思科认证考试历年真题精选8卷第2卷

Youneedtodecideonwhichtrunkingmethodtoimplementinthe

Ezonexamnetwork.WhatisacharacteristicofISLand802.1qframe,taggingina

switchedLANenvironment?

A.Theyareusedtofindthebestpaththroughanetwork.

B.Theyallowtheexchangeoffilteringtables.

C.TheyspecifydifferentimplementationsoftheSpanning-TreeProtocol.

D.Theyallowtheexchangeofroutingtables

E.Theyprovideinter-switchVLANcommunication.

正确答案：E

解析:Explanation:AtrunklinkistheothertypeofLayer2portsupportedon

Ciscoswitches.Whenatrunkportisconfigured,itbeginsmarkingframesasthey

exittheporttoindicatewhichVLANeachframe,isassociatedwith.

Thetrunkportcanalsoreadthemarkings,calledtags,astheyenterthetrunk

port.Thisenablestheswitchtosendaframe.onlytotheportsforthegiven

VLANassociatedwiththeincomingframe.Themainpurposeoftrunkingisto

carrytrafficbetweenswitchesandmaintaintheVLANinformation.

Unlikeanaccesslink,thetrunklinkdoesnotbelongtoasingleVLANbutinstead

cancarrytrafficfromseveralVLANsoverapoint-to-pointlinkbetweentwo

devicesthatunderstandtheprotocol.TwoformsoftrunkingareusedforCisco

switchesonEthernetnetworks:AnIEEEindustrystandardcalledIEEE802.IQ.

Thisisaframe-taggingmechanismthataddsaVLANidentifiertotheframe.by

insertingatagatLayer2.Anotherform,oftrunkingonCiscoswitchesiscalled

Inter-SwitchLink(ISL),whichisaCiscoproprietarytrunkingmechanism.ISLuses

aframe,encapsulationmethodthataddsaheadertoidentifytheVLAN.

IncorrectAnswers:

A,D.Thesearethefunctionsofrouters,notswitches.

B.FilteringtablescanbeusedoncertainCatalystswitchesviatheuseofVLAN

accesscontrollists,butthisinformationisneversharedbetweenswitches.

C.AseparateSTPinstanceiscreatedforeachVLANZbuttheSTPimplementation

remainsthesame.

WhichVTPmodeshouldaCiscoswitchbesettoifthisswitchistoaddor

deleteVLANstoamanagementdomain?

A.Transparent

B.Server

C.Auto

D.Client

E.User

正确答案：B

解析：

Explanation:VTPModes:IfyouintendtomakeaswitchpartofaVTPmanagementdomain

,eachswitchmustbeconfiguredinoneofthreepossibleVTPmodes.TheVTPmodeassign

edtoaswitchwilldeterminehowtheswitchinteractswithotherVTPswitchesinthemanag

ementdomain.ThethreeVTPmodesthatcanbeassignedtoaCiscoswitchincludeserver

mode,clientmode,andtransparentmode.Eachoftheserolesisoutlinedbelow:ServerM

ode:OnceVTPisconfiguredonaCiscoswitch,thedefaultmodeusedisServerMode.Inan

ygivenVTPmanagementdomain,atleastoneswitchmustbeinServerMode.WheninSer

verMode,aswitchcanbeusedtoadd,delete,andmodifyVLANs,andthisinformationwill

bepassedtoallotherswitchesintheVTPmanagementdomain.ClientMode:Whenaswit

chisconfiguredtouseVTPCIientMode,itissimplytherecipientofanyVLANsadded,delet

ed,ormodifiedbyaswitchinServerModewithinthesamemanagementdomain.Aswitch

inVTPclientmodecannotmakeanychangestoVLANinformation.TransparentMode:As

witchinVTPTransparentModewillpassVTPupdatesreceivedbyswitchesinServerMode

tootherswitchesintheVTPmanagementdomain,butwillnotactuallyprocesstheconten

tsofthesemessages.WhenindividualVLANsareadded,deleted,ormodifiedonaswitchr

unningintransparentmode,thechangesarelocaltothatparticularswitchonly,andaren

otpassedtootherswitchesintheVTPmanagementdomain.BasedontherolesofeachVT

Pmode,theuseofeachshouldbemoreorlessobvious.Forexample,ifyouhadl5Ciscoswi

tchesonyournetwork,youcouldconfigureeachofthemtobeinthesameVTPmanagem

entdomain.AlthougheachcouldtheoreticallybeleftinthedefaultServerModeJtwould

probablybeeasiertoleaveonlyoneswitchinthisconfiguration,andthenconfigureallre

mainingswitchesforVTRCIientMode.Then,whenyouneedtoadd,delete,ormodifyaVL

AN,thatchangecanbecarriedoutontheVTPServerModeswitchandpassedtoallClient

Modeswitchesautomatically.Incaseswhereyouneedaswitchtoactinarelativelystanda

lonemanner,ordonotwantittopropagateinformationaboutitsconfiguredVLANs,use

TransparentMode.IncorrectAnswers:A.AswitchinVTPTransparentModewillpassVTP

updatesreceivedbyswitchesinServerModetootherswitchesintheVTPmanagementd

omain,butwillnotactuallyprocessthecontentsofthesemessages.C,E.Thesearenotvali

dVTPmodes.D.CIientmodemerelyacceptschangesmadebytheswitchthatisconnecte

dandinSERVERmode.

为了查看路由器的E0端口上，是否挂接了访问权限表，应该使用的命令是

()

A.showaccess-list

B.showinterfaceeO

C.showipiinterfaceeO

D.showeO

正确答案：B

请参见图示10.400网络发生故障哪种机制可防止R2接收有关10.400网络

的错误更新信息()

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

路由器上端口faO/O,其最大传输速率是（）Mbit/s

A.128

B.10

C.100

D.1000

正确答案：C

一个AS由多个组织行政下控制的网络组成。

此题为判断题（对，错）。

正确答案：x

2021思科认证考试历年真题精选8卷第3卷

EzonexamismigratingtoaprivateIPaddressingscheme.Whichofthe

followingdescribetheuseofprivateIPaddresses?（Choosetwo）

A.AddresseschosenbyEtocommunicatewiththeInternet.

B.AddressesthatcannotberoutedthroughthepublicInternet.

C.AddressesthatcanberoutedthroughthepublicInternet.

D.Aschemetoconservepublicaddresses.

E.AddresseslicensedtoenterpriseorISPsbyanInternetregistry

organization.

正确答案：BD

解析:Explanation:

PrivateIPaddressspacehasbeenallocatedviaRFC1918.Thismeansthe

addressesareavailableforanyusebyanyoneandthereforethesameprivateIP

addressescanbereused.Howevertheyaredefinedasnotroutableonthepublic

Internet.Theyareusedextensivelyinprivatenetworksduetotheshortageof

publiclyregisteredIPaddressspaceandthereforenetworkaddresstranslationis

requiredtoconnectthosenetworkstotheInternet.

在相距几百英里的路由器之间使用租用线路的点到点WAN链路上，下列哪个

设备室DTE设备

A.路由器

B.CSU/DSU

C.电话局中心机房设备

D.路由器处理器上的芯片

正确答案：A

AsaEzonexamtraineeyouarerequiredtosetthedefaultgatewayona

CiscoswitchtotheIPaddressof15.WhichIOScommandshouldyou

use?

A.TestKSwitch(config)#iproute-default15

B.TestKSwitch(config)#ipdefault-gateway15

C.TestKSwitch(config)#iproute15

D.TestKSwitch(config)#ipdefault-network15

E.Noneoftheabove

正确答案：B

解析：Explanation:

Usethe"ipdefault-gateway"commandtoentertheIPaddressofthenext-hop

routerinterfacethatisdirectlyconnectedtotheswitchwhereadefaultgateway

isbeingconfigured.ThedefaultgatewayreceivesIPpacketswithunresolved

destinationIPaddressesfromtheswitch.

Oncethedefaultgatewayisconfigured,theswitchhasconnectivitytotheremote

networkswithwhichahostneedstocommunicate.

下列哪项对OSI第1层协议主要功能的描述最准确()

A成帧

B.将比特从一台设备传递到另一台设备

G编址

D.DLCI

正确答案：B

AEzonexamEthernetswitchreceivesaunicastframe,withadestinationMAC

thatislistedintheswitchtable.Whatwillthisswitchdowiththeframe?

A.Theswitchwillforwardtheframe,toaspecificport

B.Theswitchwillforwardtheframe,toallportsexcepttheportonwhichit

wasreceived

C.Theswitchwillreturnacopyoftheframe,outthesourceport

D.Theswitchwillnotforwardunicastframes

E.TheswitchwillremovethedestinationMACfromtheswitchtable

F.Noneoftheabove.

正确答案：A

A解析：Explanation:

HowDoestheSwitchFindHostMACs?

Let'susethediagrambelowtohelpusunderstandhowaddresslearningprocess

takesplace.

DataLinkAddressLearning

Mactable

FEO/O:0000.74a3.0023

/FE0/11:0000.43C5.334C

Let'sassumethatwehavejustpoweredontheswitch.IthasnothinginitsMAC

table.Weconnectthecablesfromthehostsontheswitchinterfacesasshownin

thediagram.HostAinitiatesaconnectiontowardsHostD,andthefollowing

takesplace:

1.HostA(interfacefeO/O)sendsaframe,toHostD(MAC

address:0000.43c5.334c).

2.TheswitchinspectstheSourceAddressintheframe,andnotesinitstablethe

MACaddressofHostAalongwiththeInterfacenumberfromwhichtheframe,

originated.

3.TheswitchinspectstheDestinationAddressintheframe.Sinceitdoesnot

haveHostsDMACaddressinitstable,itconstructsabroadcastframe,and

forwardsoutallinterfacesexcepttheinterfacefromwheretheoriginalframe,

arrived.

4.HostDidentifiesitselfastheexpectedrecipientandrespondsbacktoHostA.

Theswitchreceivestherespondframe,oninterfacefeO/11andplacestheSAin

itstablealongwiththeinterfacenumberwheretheframe,camefrom.

5.Fromnowon,furthercommunicationbetweenthetwohostswillbeswitched

totheappropriateinterfacesbasedontheMACtablesentries.

Thisprocesstakesplaceeverytimeanewhostisattachedontheswitchand

initiatestraffic.TheswitchtriestokeepitsMACtableup-to-date,thereforeif

somehostsdonotinitiatetrafficforacertainamountoftime,theswitchremoves

themfromitstableandreinsertsthemwhentheybeginsendingtraffic.

下列哪种广域网连接方式是电路交换（）

A.ISDN

B.E1

C.DDN

D.Frame-relay

正确答案：A

2021思科认证考试历年真题精选8卷第4卷

IP地址为:192,168.50.70,掩码为:255,255.255,248,则该IP地址所在子网

的子网有效IP为（）

A.3—9

B.1—0

C.5—0

D.6—5

正确答案：C

关于RIPV1和RIPV2,下列说法哪些正确()

A.RIPV1报文支持子网掩码

B.RIPV2报文支持子网掩码

C.RIPV2缺省使用路由聚合功能

D.RIPV1只支持报文的简单口令认证，而RIPV2支持md5认证

正确答案：BC

在配置帧中继子接口时，在物理接口上应该配置的内容是：()

A酒已置IP地址

B.封装帧中继协议

C.指定子接口类型

D.设定子接口

E.配置密码

正确答案：BCD

RIP路由在()时间内没有收到更新会删除不可达路由()

A.90S

B.120S

C.180S

D.240S

正确答案：D

在哪种提示符下可以确认是处于特权模式()

A.Router>

B.Router(config)

C.Router

D.Router(config-if)

正确答案：C

你将一台笔记本电脑直接连接到了路由器的以太网端口。为确保命令copyflash

tftp成功地完成其任务，需要满足哪三个条件?()

A.必须在路由器上运行TFTP服务器软件

B.必须在笔记本电脑上运行TFTP服务器软件

C.将笔记本电脑直接连接到路由器以太网端口的以太网电缆必须是直通电缆

D.笔记本电脑与路由器以太网接口必须位于同一个子网

E.必须给命令copyflashtftp提供笔记本电脑的IP地址

F.路由器闪存必须有足够的空间，能够存储要复制的文件

答案：BDE

2021思科认证考试历年真题精选8卷第5卷

CiscoIOS命令ipnatinsidesourcestatic的作用是什么()

A.为所有的外部NAT创建一个全局的地址池

B.为内部的静态地址创建动态的地址池

C.它为所有内部本地PAT创建创建了动态源地址转换

D.为内部本地地址和内部全局地址创建一对一的映射关系

正确答案：D

路由器上激活端口的命令是（）

A.shutdown

B.noshutdown

C.up

D.noup

正确答案：B

哪种类型的验证使用三次握手()

A.HDLC

B.PPP

C.PAP

D.CHAP

正确答案：D

Whichofthefollowingstatementscorrectlydescribethedifferences

betweenhalf-duplexandfull-duplexEthernet?(Selecttwoanswerchoices.)

A.Full-duplexEthernetusesCSMA/CDtopreventcollisions.

B.Half-duplexEthernetusesaloopbackcircuittodetectcollisions.

C.Afull-duplexEthernetcardallows20Mbpsfordatatransmission.

D.Full-duplexEthernetmakesuseoftwopairsofwiresfordata.

E.AnEthernethubcanoperatebothhalfandfullduplexsimultaneously.

正确答案：BD

解析:Explanation:

Half-duplexEthernetsendandreceivesonthesameline,soaloopbackneedsto

besettodetectcollisions.Alternatively,full-dupleEthernetdoesn'thaveto

becauseitusestwopairsofwire,onetosendandtheothertoreceive.Collisions

arenotpossibleonfullduplexEthernetnetworks.

IncorrectAnswers:

A.Fullduplexusesbothpairsofwires,sotransmissionsaresentonthefirstpair,

anddatathatisreceivedcomeinontheotherpair.Thispreventscollisions.

C.Fullduplexallowsfordatatobesentandreceivedatthesametime.Itwillnot

doubletheamountofbandwidthatanygiventime.ThespeedoftheEthernet

linkwillremainat10/100.

E.Hubsareshareddevicesandcanonlysupportonemode,unlikeswitches.

RIP路由协议采用哪些方法来避免路由环路？（）

A.水平分割

B.毒性逆转

C.最大跳数

D.触发更新

正确答案：ABCD

FTP工作在OSI哪一层（）

A会话层

B.表不层

C.传输层

D.应用层

正确答案：D

2021思科认证考试历年真题精选8卷第6卷

IP扩展访问列表的数字标示范围是多少（）。

A.0-99

B.1-99

C.100-199

D.101-200

正确答案：C

WhatisthesubnetforthehostIPaddress/22?

A.

B.

C.

D.

E.

F.Noneoftheabove

正确答案：C

C解析:Explanation:

Thisquestionismucheasierthenitappearswhenyouconvertittobinaryanddo

theBooleanoperationasshownbelow:

IPaddress=10101100.00010000.11010010.00000000

/22mask=11111111.11111111.11111100.00000000

ANDresult=11111111.11111111.11010000.00000000

ANDindecimal172.16.208.0

以下对路由优先级的说法，正确的是()

A仅用于RIP和OSPF之间

B.用于不同路由协议之间

C.是路由选择的重要依据

D.直接路由的优先级缺省为0

正确答案：BCD

你在路由器上执行如下命令并重启路由器，路由器将如何

做?Router(config)#bootsystemflashc2800nm-advsecurityk9-mz.l51-4.M6.bin

Router(config)#config-register0x2101Router(config)#dosh

ver[outputcut]Configurationregisteris0x2102(willbe0x2101atnextreload)()

A.路由器将解压缩并运行闪存中的IOS文件c2800-advsecurityk9-mz.l51-

4.M6.bin

B.路由器将进入设置模式

C.路由器将加载ROM中的微型IOS

D.路由器将进入ROM监视器模式

答案：C

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

网关的功能()

A.过滤数据包

B.不同网段通信

C.校验数据帧

D.把数据封装成"段"

正确答案：B

2021思科认证考试历年真题精选8卷第7卷

VE1isaswitchintheEzonexamnetwork.WhywillVE1neverlearnthe

broadcastaddress?

A.Broadcastframesareneversenttoswitches

B.Abroadcastframe,isneverforwardedbyaswitch

C.Broadcastsonlyusenetworklayeraddressing

D.Abroadcastaddresswillneverbethesourceaddressofaframe

E.Broadcastaddressesuseanincorrectformatfortheswitchingtable

F.Noneoftheabove

正确答案：D

D

对于路由表，下列说法中正确的是：()

A.在缺省的情况下，如果一台路由器同时运行了RIP和OSPF两种动态路由协

议，则在路由表中只会显示RIP发现的路由，因为RIP协议的优先级更高

B.在缺省的情况下，如果一台路由器同时运行了RIP和OSPF两种动态路由协

议，则在路由表中只会显示OSPF发现的路由，因为OSPF协议的优先级更高

C.在缺省的情况下，如果一台路由器同时运行了RIP和OSPF两种动态路由协

议，则在路由表中只会显示RIP发现的路由，因为RIP协议的花费值(metric)更

小

D.在缺省的情况下，如果一台路由器同时运行了RIP和OSPF两种动态路由协

议,则在路由表中只会显示OSPF发现的路由，因为OSPF协议的花费值

(metric)更小

正确答案：B

请参见图示突出显示的值2表示什么意思()

R2fshoviproute

《卷路瓜分，出)

Gatewayoflaatresortisnotset

R/24[120/1]via,00:00:24,SerialO/0

C/24isdirectlyconnected,SeciaI0/0

C/24isdirectlyconnected,FastEchetnetO/O

C/24isdirectlyconnected,Seri&lO/l

R/24[120/1]via,00:00:26,SerialO/1

R/24[120/1]via,00:00:24,Serial0/0

[120/1]via,00:00:26,SerlA10/l

R/24[120/1]via,00:00:26,SerialO/1

R/24[120/2]via,00:00:26,SerialO/1

A.路由协议的管理距离

B.R2到/24网络之间的跳数

C.DUAL算法使用该值来确定该链路的带宽

D.收敛时间，单位为秒

正确答案：B

哪个命令用来设置Cisco设备串行接口的默认封装()

A.Router(config)encapsulatior)hdlc

B.Router(config)encapsulatior)defaulthdlc

C.Router(config-if)encapsulationhdlc

D.Router(config-if)encapsulationppp

正确答案：C

OSPF协议中DR和BDR使用的组播地址是()

A.

B.

C.

D.

正确答案：B

标准访问控制列表应被放置的最佳位置是在（）。

A.越靠近数据包的源越好

B.越靠近数据包的目的地越好

C.无论放在什么位置都行

D.入接口方向的任何位置

正确答案：B

2021思科认证考试历年真题精选8卷第8卷

Whichoneofthefollowingcharacteristicsistrueregardingtheuseofhubs

andswitches?

A.HubscanhavetheirportsbeconfiguredwithVLANs

B.Usinghubsiscostlywithregardtobandwidthavailability.

C.Switchescannotforwardbroadcasts.

D.Switchesaremoreefficientthanhubsinprocessingframes.

E.Switchesincreasethenumberofcollisiondomainsinthenetwork.

正确答案：E

解析：