21年思科認(rèn)證歷年真題5輯

21年思科認(rèn)證歷年真題5輯第1輯

HDLC是一種面向()的鏈路層協(xié)議。

A.希

B比特

C信元

D.數(shù)據(jù)包

正確答案：B

請(qǐng)參見圖示1040.0網(wǎng)絡(luò)發(fā)生故障哪種機(jī)制可防止R2接收有關(guān)網(wǎng)絡(luò)

的錯(cuò)誤更新信息()

A.水平分割

B.抑制計(jì)時(shí)器

C.路由毒化

D.觸發(fā)更新

正確答案：A

都是NAT的地址轉(zhuǎn)換方式()。

A靜態(tài)地址轉(zhuǎn)換

B.動(dòng)態(tài)地址轉(zhuǎn)換

C.復(fù)用動(dòng)態(tài)地址

D.端口地址轉(zhuǎn)換

正確答案：ABD

GiventhatyouhaveaclassBIPaddressnetworkrange,whichofthesubnet

masksbelowwillallowfor100subnetswith500usablehostaddressesper

subnet?

A.

B.

C.

D.

E.24

正確答案：c

解析:Explanation:

Usingthe2n-2formulaforhostaddresses,29-2=510hostaddress,soa9-bit

subnetmaskwillprovidetherequirednumberofhostaddresses.Ifthese9bits

areusedforthehostsinaclassBnetwork,thentheremaining7bitsareusedfor

thenumberofnetworks.

Againusingthe2n-2formula,wehave2n-2=126networksthatareavailable.

IncorrectAnswers:

A.Thiswillprovideforonly1networkwith216-2=65534hosts

B.Thisw川providefor6networkswith8190hostaddresses.

D.Thiswillprovide254networksand254hosts.

E.Thiswillprovide2046differentnetworks,buteachnetworkwillhaveonly30

hosts.

TheEzonexamnetworkadministratorhasjustissuedthe"switchporttrunk

nativevlan998"commandonswitchVE2.Whatisthefunctionofthiscommand?

A.ItdesignatesVLAN998asthedefaultforallunknowntaggedtraffic

B.ItdesignatesVLAN998foruntaggedtraffic

C.ItblocksVLAN998trafficfrompassingonthetrunk

D.ItcreatesaVLAN998interface

E.Noneoftheabove

正確答案：B

RIP路由協(xié)議每隔()秒進(jìn)行路由更新。

A.30

B.60

C.120

D.180

正確答案：A

下面哪個(gè)命令將新的思科IOS版本復(fù)制到路由器?()

A.copyflashftp

B.copynvramflash

C.copyflashtftp

D.copytftpflash

答案：D

21年思科認(rèn)證歷年真題5輯第2輯

默認(rèn)情況下，RIP定期發(fā)送路由更新的時(shí)間是()

A.15S

B.30S

C.60S

D.90S

正確答案：B

RIP路由協(xié)議采用哪些方法來(lái)避免路由環(huán)路？()

A.水平分割

B.毒性逆轉(zhuǎn)

C.最大跳數(shù)

D.觸發(fā)更新

正確答案：ABCD

在OSI七層模型中，介質(zhì)工作在哪一層()

A傳輸層

B.會(huì)話層

C物壬醺

D.應(yīng)用層

正確答案：C

路由器下"特權(quán)用戶模式”的標(biāo)識(shí)符是：（）

A.>

B.!

C.

D.(config-if)

正確答案：C

AsaCCNAcandidate,youmustknowthevariouslayersoftheOSImodel.At

whichlayersoftheOSIModeldoWideAreaNetworksoperatein?(Choosetwo)

A.PhysicalLayer

B.DatalinkLayer

C.NetworkLayer

D.SessionLayer

E.TransportLayer

F.PresentationLayer

G.ApplicationLayer

正確答案：AB

A,B解析:Explanation:

AWANisadatacommunicationsnetworkthatcoversarelativelybroad

geographicareaandthatoftenusestransmissionfacilitiesprovidedbycommon

carriers,suchastelephonecompanies.WANtechnologiesgenerallyfunctionat

thelowertwolayersoftheOSIreferencemodel:thephysicallayerandthedata

linklayerasshownbelow.

OSIlayersWANspecificallon*

NetworK

layerc

n

d

eln

x

2d2

o0d

d口

dHS

MACE

sublayer

EIA/TIA232

PhysicalEIA/TIA449

layerV24V35

為HSSIG.7O3

L

7EIA-530

X

Note:OccasionallyWAN'swouldalsobeconsideredtooperateatlayer3,but

sincethisquestionaskedforonly2chopiceslayers1and2arebetterchoices.

幀中繼環(huán)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

正確答案：B

在路由表中到達(dá)同一網(wǎng)絡(luò)的路由有：靜態(tài)路由、RIP路由、IGRP路由，OSPF

路由，則路由器會(huì)選用哪條路由傳輸數(shù)據(jù)：（）

A.靜態(tài)路由

B.RIP路由

C.IGRP路由

D.OSPF路由

正確答案：A

21年思科認(rèn)證歷年真題5輯第3輯

以下特殊區(qū)域中哪一個(gè)沒有自動(dòng)下發(fā)缺省路由（）

A.末梢區(qū)域

B.完全末梢區(qū)域

C.NSSA區(qū)域

D.完全NSSA區(qū)域

正確答案：D

YouwishtosegmentyourLANintomultiplebroadcastdomains.Which

technologymethodshouldyouimplementinordertodothis?

A.Transparentbridging

B.Cut-throughswitching

C.Fragment-freeswitches

D.VirtualLANs

E.Store-and-forwardswitching

F.Noneoftheabove

正確答案：D

D解析：Explanation:

ThecreationofVLANsinaswitchwillprovideseparateBroadcastdomains.By

default,allportsinaCatalystswitchbelongtoVLAN1.Bycreatingadditional

VLANs,theLANwillbelogicallysegmentedintoseparatebroadcastdomains.

IncorrectAnswers

A.TransparentbridgingiscalledTransparentbecausetheendpointsdevicesdo

notneedtoknowthatthebridgesexists.Itwillnotplayanyroleforcreating

separatebroadcastdomain

B,E.Bothoftheseareswitchingmethods.

C.Thishasnothingtodowiththecreationofmultiplebroadcastdomains.

請(qǐng)參見圖示。主機(jī)A無(wú)法訪問Internet。此問題的原因是什么

A.主機(jī)A的IP地址不正確

B.主機(jī)A的默認(rèn)網(wǎng)關(guān)不正確

C.兩臺(tái)路由器的FaO/1接口配置了不同的子網(wǎng)

D.RlFaO/O的子網(wǎng)掩碼不正確

正確答案：C

EzonexamisusingIPaddressingaccordingtoRFC1918.Whichthreeaddress

rangesareusedforinternalprivateaddressblocksasdefinedbyRFC1918?

(Chooseallthatapply)

A.to255.255.255

B.to55

C.to55

D.to55

E..to55

F.to55

G.to55

正確答案：BDF

B,D,F解析：Explanation:

RFC1918definesthreedifferentIPaddressrangesasprivate,meaningthatthey

canbeusedbyanyprivatenetworkforinternaluse,andtheserangesarenotto

beusedintheInternet.TheclassAprivaterangeisto55.

TheclassBaddressrangeisto55.TheclassCprivateIP

addressrangeisto55.

IncorrectAnswers:

A.Thenetworkaddressisinvalidandcannotbeused.

C.Thecorrectaddressrangeis172.16.X.Xthrough172.31.X.X

E.TheaddressisreservedfortheinternalloopbackIPaddress,butthe

entire127.X.X.XrangeisnotdefinedinRFC1918asaprivateaddressrangefor

networks.

G.ThisaddressrangedescribestheclassDmulticastaddressrange.

交換機(jī)工作在OSI七層模型的哪一層()

A.物理層

B.數(shù)據(jù)鏈路層

C.網(wǎng)絡(luò)層

D.傳輸層

正確答案：B

要將許可證復(fù)制到閃存，可使用哪個(gè)命令?()

A.copytftpflash

B.savelicenseflash

C.licensesaveflash

D.copylicenseflash

答案：C

Whenyoucomparethedifferencesbetweenhalf-duplexandfull-duplex

Ethernet,whichofthefollowingcharacteristicsareexclusivetohalf-duplex?

(Selecttwoanswerchoices)

A.Half-duplexEthernetoperatesinasharedcollisiondomain.

B.Half-duplexEthernetoperatesinanexclusivebroadcastdomain.

C.Half-duplexEthernethasefficientthroughput.

D.Half-duplexEthernethaslowereffectivethroughput.

E.Half-duplexEthernetoperatesinanexclusivecollisiondomain.

正確答案：AD

解析：Explanation:

Asingledevicecouldnotbesendingaframe,andreceivingaframe,atthesame

timebecauseitwouldmeanthatacollisionwasoccurring.So,devicessimply

chosenottosendaframe,whilereceivingaframe.Thatlogiciscalledhalf-

duplexlogic.

Ethernetswitchesallowmultipleframestobesentoverdifferentportsatthe

sametime.Additionally,ifonlyonedeviceisconnectedtoaswitchport,thereis

neverapossibilitythatacollisioncouldoccur.So,LANswitcheswithonlyone

devicecabledtoeachportoftheswitchallowtheuseoffull-duplexoperation.

FullduplexmeansthatanEthernetcardcansendandreceiveconcurrently.

IncorrectAnswers:

B.Fullduplexeffectivelydoublesthethroughputofhalf-duplexoperation,

becausedatacanbebothsentandreceivedatthefull10/100speed.

C,E.Inhalfduplexoperation,thenetworkissharedbetweenalldevicesinthe

collisiondomain.

21年思科認(rèn)證歷年真題5輯第4輯

IP擴(kuò)展訪問列表的數(shù)字標(biāo)示范圍是多少（）。

A.0-99

B.1-99

C.100-199

D.101-200

正確答案：C

Whiletroubleshootingaconnectivityproblemonthenetwork,youissuethe

pingcommandfromyourPCcommandprompt,buttheoutputshows"request

timesout."

AtwhichOSIlayeristhisproblemassociatedwith?

A.Thedatalinklayer

B.Theapplicationlayer

C.Theaccesslayer

D.Thesessionlayer

E.Thenetworklayer

正確答案：E

解析:Explanation:

TCP/IPincludesICMP,aprotocoldesignedtohelpmanageandcontrolthe

operationofaTCP/IPnetwork.TheICMPprotocolprovidesawidevarietyof

informationaboutanetwork'shealthandoperationalstatus.Controlmessageis

themostdescriptivepartofaname.ICMPhelpscontrolandmanageIP'swork

andthereforeisconsideredpartofTCP/IP'snetworklayer.

對(duì)于使用鏈路狀態(tài)路由協(xié)議的路由器如何選擇最佳路線到達(dá)子網(wǎng)，下列哪項(xiàng)是

正確的（）

A.路由器會(huì)發(fā)現(xiàn)鏈路狀態(tài)數(shù)據(jù)庫(kù)中的最佳路由

B.通過針對(duì)鏈路狀態(tài)數(shù)據(jù)庫(kù)中的信息運(yùn)行SPF算法，路由器會(huì)計(jì)算出最佳路由

C.路由器將比較每個(gè)鄰居接收到的更新中為子網(wǎng)列出的標(biāo)準(zhǔn)，并挑選最佳標(biāo)準(zhǔn)

路由

D.路由器會(huì)使用具有最低條數(shù)的路徑

正確答案：B

WhichofthefollowingcomponentsmustbeelectedbeforetheSpanning

TreeProtocolcanconvergeinaswitchedLAN?

A.Designatedports.

B.Duplexoperatingmode.

C.Fastmodeports.

D.Rootbridge.

E.Rootports.

F.BDPUpriority.

正確答案：ADE

A,D,E解析:Explanation:

Designatedport:Eitherarootportoraportthathasbeendeterminedashaving

thebest(lower)cost-adesignatedportwillbemarkedasaforwardingport.

Rootbridge:TherootbridgeisthebridgewiththebestbridgeID.WithSTP,the

keyisforalltheswitchesinthenetworktoelectarootbridgethatbecomesthe

focalpointinthenetwork.Allotherdecisionsinthenetwork-likewhichportisto

beblockedandwhichportistobeputinforwardingmode-aremadefromthe

perspectiveofthisrootbridge.

Rootport:Alwaysthelinkdirectlyconnectedtotherootbridge,ortheshortest

pathtotherootbridge.Ifmorethanonelinkconnectstotherootbridge,thena

portcostisdeterminedbycheckingthebandwidthofeachlink.Thelowestcost

portbecomestherootport.

Sothesethreecomponentsmustbeelectedbeforethespanningtreeprotocol

canconvergeinaswitchedLAN

命令ipnatpoolaaa0netmask的作用是()

A.指定可訪問地址

B.定義地址池

C.指定路由

D.定義哪些地址可以進(jìn)行地址轉(zhuǎn)換

正確答案：B

OSPF協(xié)議中，ABR的不同端口可能運(yùn)行在不同的area中，其中一定有接口

運(yùn)行在（）當(dāng)中.

A.areaO

B.areal

C.arealO

D.arealOO

正確答案：A

Showcdpinterface命令是用于顯示以下哪一項(xiàng)的（）

A.CDP的時(shí)間值和接口狀態(tài)

B.鄰居路由器的接口配置

C.鄰居設(shè)備的IP地址

D.CDP保持時(shí)間

正確答案：A

21年思科認(rèn)證歷年真題5輯第5輯

YouaretryingtoconnectdirectlyintotheLANprotofaEzonexamrouter.

YouwanttotelnettothelocalCiscorouterusingTCP/IPbutcannotcreatea

session.

Whatshouldyoudotoresolvetheproblem?

A.Useastraight-throughcabletoconnectyourcomputer'sCOMporttothe

router'sconsoleport.

B.Useacrossovercabletoconnectyourcomputer'sCOMporttothe

router'sconsoleport.

C.Useastraight-throughcabletoconnectyourcomputer'sCOMporttothe

router'sEthernetport.

D.Useacrossovercabletoconnectyourcomputer'sEthernetporttothe

router'sEthernetport.

E.Usearollovercabletoconnectyourcomputer'sEthernetporttothe

router'sEthernetport.

F.Useastraight-throughcabletoconnectyourcomputer'sEthernetportto

therouter'sEthernetport.

G.Noneoftheabove

正確答案：D

D解析:Explanation:

Inordertoconnectdirectlytoarouterviatelnet,youmustconnecttotherouter

viaoneoftheLANports.WhenconnectingdirectlytotheEthernetportwithaPC

withouttheuseofaswitchorhub,acrossovercablemustbeused.

IncorrectAnswers:

A,B,C.InordertotelnetdirectlyintotherouterviaaTCP/IPconnection,the

COMportofthePCcannotbeused.TheCOMportisusedfordirectterminal

emulationprogramssuchasHyperTerminal.

E.Rollovercablesareusedforconsoleconnectionsintotherouter,notforTCP/IP

connections.

F.Straightthroughcablesareusedforconnectionsintoaswitchorhubfromthe

PC.ItwillnotworkfordirectEthernetconnectionsintotherouter.

WhichofthefollowingareVLANframe,encapsulationtypesthatmaybe

configuredonaCatalystswitch?(Choosetwo.)

A.VTP

B.ISL

C.CDP

D.802.1Q

E.802.1p

F.LLC

正確答案：BD

B,D解析：Explanation:

ThetwoVLANtrunkingencapsulationtypesare:

Inter-SwitchLink(ISL):ThisisproprietarytoCiscoswitches,andit'susedforFast

EthernetandGigabitEthernetlinksonly.ISLroutingcanbeusedonaswitchport,

routerinterfaces,andserverinterfacecardstotrunkaserver.ISLletsyou

explicitlytagVLANinformationontoanEthernetframe.Thistagginginformation

allowsVLANstobemultiplexedoveratrunklinkthroughanexternal

encapsulationmethod,whichallowstheswitchtoidentifytheVLANmembership

ofaframe,overthetrunkedlink.

IEEE802.1Q:CreatedbytheIEEEasastandardmethodofframe,tagging,this

actuallyinsertsafieldintotheframe,toidentifytheVLAN.Ifyou'retrunking

betweenaCiscoswitchedlinkandadifferentbrandofswitch,youhavetouse

802.1Qforthetrunktowork.

AstheEzonexamnetworkadministrator,youarerequiredtohaveafirm

understandingoftheOSImodel.Whydoesthedatacommunicationindustryuse

thelayeredOSIreferencemodel?(Choosetwo)

A.Itenablesequipmentfromdifferentvendorstousethesameelectronic

components,thussavingresearchanddevelopmentfunds

B.Itencouragesindustrystandardizationbydefiningwhatfunctionsoccur

ateachlayerofthemodel

C.Itdividesthenetworkcommunicationprocessintosmallerandsimpler

components;thusaidingcomponentdevelopment,designandtroubleshooting

D.Itprovidesameansbywhichchangesinfunctionalityinonelayer

requirechangesinotherlayers

E.Itsupportstheevolutionofmultiplecompetingstandardsandthus

providesbusinessopportunitiesforequipmentmanufacturers

正確答案：BC

解析:Explanation:

TheOSI(OpenSystemInterconnection)referencemodelwascreatedasa

referencepointforcommunicationsdevices.Alayeredapproachisusedto

segmenttheentiretelecommunicationsprocessintoaseriesofsmallersteps.

Aiscorrectbecauseitencouragesalevelofstandardizationbyencouragingthat

functionsbecomparedtoknownlayers.

Disalsocorrectbecauseitallowsengineerstofocusonthedevelopment,

refining,andperfectionofsimplercomponents.

交換機(jī)的三大功能為(