2021思科認(rèn)證考試真題6節(jié)

2021思科認(rèn)證考試真題6節(jié)第1節(jié)

下列哪項(xiàng)OSI第2層功能是由PPP協(xié)議標(biāo)準(zhǔn)規(guī)范，但使用CISCO專有的

HDLC報(bào)頭字段實(shí)現(xiàn)

A成幀

B.尋址

C.錯誤檢測

D識別幀內(nèi)的協(xié)議類型

正確答案：D

CHAP驗(yàn)證時(shí),將對方的主機(jī)名HOST作為自己的用戶名USER。

此題為判斷題（對，錯）。

正確答案：V

YouhavesetupanInternetbasedFTPserver,wherepeoplecanuploadand

downloadfiles.IntermsoftheOSImodel,whatisthehighestlayerusedduring

theFTPsessions.

A.Application

B.Presentation

C.Session

D.Transport

E.Internet

F.DataLink

G.Physical

正確答案：A

A解析：Explanation:

Theapplicationlayeristhehighestlayer(layer7)oftheOSImodel,andis

reservedforenduserapplications.SinceFTPisitselfanapplication,layer7isthe

highestlayerused.

IncorrectAnswers:

B,C,D,E,F,G.InanygivenFTPsession,alloftheselayerswillbeusedatsome

pointbuttheyareincorrectbecausethequestionaskedforthehighestlayer

usedbyFTP.

幀中繼環(huán)境中,CIR的含義是()

A.提高線路速率

B.保證線路速率

C.降低線路速率

。配置線路速率

正確答案：B

下列哪兩項(xiàng)用于在配置OSPF路由進(jìn)程時(shí)確定路由器ID()

A.第一個快速以太網(wǎng)接口的1P地址

B.任何邏輯接口的最大IP地址

C.任何物理接口的最大IP地址

D.默認(rèn)網(wǎng)關(guān)的IP地址

E.優(yōu)先級為1的任何物理接口

正確答案：BC

2021思科認(rèn)證考試真題6節(jié)第2節(jié)

某網(wǎng)絡(luò)中，擬設(shè)計(jì)10子網(wǎng)，每個子網(wǎng)中放有14臺設(shè)備，用IP地址段為

199.41.10.X,請問符合此種規(guī)劃的子網(wǎng)掩碼是()

A.

B.

C.40

D.

正確答案：C

OSPF在同一區(qū)域內(nèi)，下列說法正確的是（）

A.每臺路由器生成的LSA都是相同的

B.每臺路由器的LSDB（鏈路狀態(tài)數(shù)據(jù)庫）都是相同的

C.每臺路由器根據(jù)該LSDB計(jì)算出的最短路徑樹都是相同的

D.每臺路由器根據(jù)該最短路徑樹計(jì)算出的路由都是相同的

正確答案：B

以下哪個命令讓路由器在show之后顯示有效的參數(shù)列表

A.sh?

B.show?

C.show?

D.showhelp

正確答案：C

TheEzonexamnetworkTopologyisdisplayedintheexhibitbelow:

AswitchhasbeenconfiguredforthreedifferentVLANs:VLAN2,VLAN3,

andVLAN4.ForthepurposesofcommunicationbetweenVLANsarouteristobe

added.HostfromoneVLANshouldbeabletoreachthehostsintheother

VLANs.

Basedonthisrequirement,whattypeofconnectionisacceptablebetween

therouterandswitch?

(Selectallvalidanswers)

A.10MbpsEthernet

B.56kbpsserial

C.100MbpsEthernet

D.1,544Mbpsserial

E.1000MbpsEthernet

正確答案：CE

解析：Explanation:Forallhoststobeabletoreacheachother,inter-

VLANroutingwillneedtobeconfigured.Inordertoprovidelnter-

VLANroutingbetweentherouterandtheswitch,atrunkwillneedtobesetup.Thistrunkca

nbeeitherISLor802.1Q.Onarouter,theinterfacethatistobeusedasthetrunkcanbel00

MbpsEthernetGigabitEthernetorlOGigabitEthernet.Therefore^nlychoicesCorEare

correct.

WithregardtoEthernetmediaaccessmethods,whichofthefollowingare

true?

(Chooseallthatapply.)

A.Adevicewaitsforanelectronicsignalbeforetransmitting.

B.Adevicelistensandwaitsuntilthemediaisnotbusybeforetransmitting.

C.AlldevicesonanEthernetsegmentseedatathatpassesonthenetwork

medium.

D.Onlythesenderandthereceiverdevicesseedatathatpassesonthe

networkmedium.

E.Ethernetnetworksallowyoutoconfigureddeviseswithhigher

transmissionpriority.

正確答案：BC

解析：Explanation:

EthernetusestheCSMA/CDaccessmethod.

CSMA/CDlogichelpspreventcollisionsandalsodefineshowtoactwhena

collisiondoesoccur.TheCSMA/CDalgorithmwordslikethis:

1.Adevicewithaframe,tosendlistensuntiltheEthernetisnotbusy.

2.WhentheEthernetisnotbusy,thesenderbeginssendingtheframe.

3.Thesenderlistenstomakesurethatnocollisionoccurred.

4.Oncethesendershearthecollision,theyeachsendajammingsignal,to

ensurethatallstationsrecognizethecollision.

5.Afterthejammingiscomplete,eachsenderrandomizesatimerandwaitsthat

long.

6Wheneachtimerexpires,theprocessstartsoverwithStep1.

So,alldevicesontheEthernetneedtouseCSMA/CDtoavoidcollisionsandto

recoverwheninadvertentcollisionsoccur.

2021思科認(rèn)證考試真題6節(jié)第3節(jié)

osi七層模型中，數(shù)據(jù)鏈路層的數(shù)據(jù)封裝名稱為（）

A.比特

B幀

C包

D.段

正確答案：B

AfterworkingallnightandsuccessfullyconfiguringaCiscorouterforthe

Ezonexamnetworkyousaveyourchangesonthestartupconfig,rebootthe

router,andgooutforacigarette.Whenyoureturn,noneofyourchangesare

activeandtherouterbootstotheinitialconfigurationmode!Whichofthe

choicesbelowindicatesthesourceofyourproblem?

A.HardwarefailureinNVRAMpreventstherouterfromloadingtheconfig

B.Startup-configinflashiscorruptandcannotbeanalyzed

C.Routerconfiguration-registersettobypassstartupconfiguration

D.Startup-configinNVRAMiscorruptandcannotbeanalyzed

E.Noneoftheabove

正確答案：C

解析：Explanation:

Thedefaultconfiguration-registersettingof0x2102loadstheIOSfromflashand

theconfigurationfromNVRAM.

However,forpasswordrecovery,youcansettheregisterto0x2142andthe

startup-configfileinNVRAMwillbebypassed.Theproblemdescribedhereis

thattheconfigregisterwasnotchangedbackto0x2102beforetherouterwas

rebooted,sotheactiveconfigurationisbypassed.Simplysettingtheconfig

registerbackto0x2102willfixthisproblem.

IncorrectAnswers:

A,B,D.Allofthesedescribehardwareorsoftwareerrors.Intheeventthatthisis

theproblem,errorswillbegeneratedandtherouterwillfailtobootproperly.In

thesecases,therouterwillnotreturntotheinitialstartupconfiguration.

混合型協(xié)議既具有〃距離矢量路由協(xié)議”的特性，又具有“鏈路狀態(tài)路由協(xié)議'’的

特性，下列協(xié)議中屬于混合型協(xié)議的是：（）

A.RIP

B.OSPF

C.EIGRP

D.IGRP

正確答案：C

下列哪一設(shè)備工作時(shí)，要用到OSI的七個層（一層到七層）（）

A.PC

B.網(wǎng)管機(jī)

C.WEB服務(wù)器

D.交換機(jī)

E.路由器

正確答案：ABC

配置LACP時(shí),在要使用的接口上必須將哪三個參數(shù)配置得完全相同?（）

A.虛擬MAC地址

B端口速度

C.雙工模式

D.PortFast

E.VLAN信息

答案：BCE

2021思科認(rèn)證考試真題6節(jié)第4節(jié)

TheEzonexamnetworkadministratorhasjustissuedthe"switchporttrunk

nativevlan998"commandonswitchVE2.Whatisthefunctionofthiscommand?

A.ItdesignatesVLAN998asthedefaultforallunknowntaggedtraffic

B.ItdesignatesVLAN998foruntaggedtraffic

C.ItblocksVLAN998trafficfrompassingonthetrunk

D.ItcreatesaVLAN998interface

E.Noneoftheabove

正確答案：B

下列哪項(xiàng)OSI第2層功能是由PPP協(xié)議標(biāo)準(zhǔn)規(guī)范，但使用CISCO專有的

HDLC報(bào)頭字段實(shí)現(xiàn)

A成幀

B.尋址

C.錯誤檢測

D識別幀內(nèi)的協(xié)議類型

正確答案：D

下列路由協(xié)議中，屬于鏈路狀態(tài)路由協(xié)議的是（）

A.RIP

B.EIGRP

C.IGRP

D.OSPF

正確答案：D

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.

為將當(dāng)前運(yùn)行的配置復(fù)制到TFTP服務(wù)器上，需要哪個命令？（）

A.copyrunning-configtftp

B.copystartup-configtftp

C.copytftprunning-config

D.copytftpstartup-config

正確答案：A

2021思科認(rèn)證考試真題6節(jié)第5節(jié)

InaswitchedLANnetwork,whatistheSpanning-Treealgorithmusedfor?

A.Itisusedtoprovideamechanismforroutingupdatesinswitched

environments.

B.Itisusedtopreventroutingloopsinnetworkswithredundantroutes.

C.Itisusedtopreventswitchingloopsinnetworkswithredundantswitched

routes.

D.Itisusedtomanage,theaddition,deletion,andnamingofVLANsacross

multipleswitches.

E.Itisusedtosegmentanetworkintomultiplecollisiondomains.

F.Noneoftheabove.

G.AlloftheabovearefunctionsofSTP.

正確答案：C

C解析：Explanation:

Toavoidloops,allbridgingdevices,includingswitches,useSTP.STPcauseseach

interfaceonabridgingdevicetosettleintoablockingstateoraforwardingstate.

Blockingmeansthattheinterfacecannotforwardorreceivedataframes.

Forwardingmeansthattheinterfacecansendandreceivedataframes.Byhaving

acorrectsubsetoftheinterfacesblocked,asinglecurrentlyactivelogicalpath

willexistbetweeneachpairofLANs.STPresidesatthedatalinklayer,soitis

usedtopreventloopswithinaswitchednetwork.Itisnotusedtopreventrouting

loops;thatisthefunctionofthemechanismswithnaroutingprotocol.

當(dāng)拓?fù)湫畔⑼瓿山粨Q，相鄰路由器具有相同的LSDB時(shí)，下列哪項(xiàng)OSPF鄰居

狀態(tài)是希望得到的()

A.2-WAY

B.FULL

C.Exchange

0.Loading

正確答案：B

關(guān)于PPP和HDLC的說法中，錯誤的是（）

A.PPP是通用協(xié)議，HDLC是CISCO私有協(xié)議

B.PPP有驗(yàn)證功能,HDLC無驗(yàn)證功能

C.PPP效率低，HDLC效率高

D.在配置ISDN時(shí)，廣域網(wǎng)協(xié)議不能封裝成PPP,但可以封裝成HDLC

正確答案：D

關(guān)于靜態(tài)NAT，下面（）說法是正確的。

A.靜態(tài)NAT轉(zhuǎn)換在缺省情況下24小時(shí)后超時(shí)

B.靜態(tài)NAT轉(zhuǎn)換從地址池中分配

C.靜態(tài)NAT將內(nèi)部地址一對一靜態(tài)映射到內(nèi)部全局地址

D.CISCO路由器缺省使用了靜態(tài)NAT

正確答案：C

CDPisbeingusedthroughouttheEzonexamnetwork.Whataretworeasons

whytheEzonexamnetworkadministratorwoulduseCDP?（Choosetwo）

A.Todeterminethestatusofnetworkservicesonaremotedevice

B.ToobtaintheIPAddressofaconnecteddeviceinordertotelnettothe

device

C.Toverifythetypeofcableinterconnectingtwodevices

D.ToverifyLayer2connectivitybetweentwodeviceswhenLayer3fails

E.ToobtainVLANinformationfromdirectlyconnectedswticehs

F.Todeterminethestatusoftheroutingprotocolsbetweendirectly

connectedrouters

G.Tosupportautomaticnetworkfailoverduringoutages

正確答案：BD

B,D

2021思科認(rèn)證考試真題6節(jié)第6節(jié)

Ezonexamusershavenoticedextremelyslownetworkperformance,

intermittentconnectivity,andconnectionlosses.Afterenteringthe"show

interfaces"command,younoticethattheEthernetinterfaceisconfiguredas100

Mbpsfull-duplexandthatthereisevidenceoflatecollisions.Whatcouldbethe

causeofthisproblem?

A.Duplexmismatch

B.Aroutingloop

C.Trunkingmodemismatch

D.Improperlyconfiguredrootbridge

E.ImproperlyconfiguredstaticVLAN

F.Noneoftheabove

正確答案：A

A解析：Explanation:

Aduplexmismatchmayresultinperformanceissues,intermittentconnectivity,

andlossofcommunication.WhentroubleshootingNICissues,verifythattheNIC

andswitchareusingavalidconfiguration.Somethird-partyNICcardsmayfall

backtohalf-duplexoperationmode,eventhoughboththeswitchportandNIC

configurationhavebeenmanuallyconfiguredfor100Mbps,full-duplex.

Thisbehavior,isduetothefactthatNICautonegotiationlinkdetectionisstil

operatingwhentheNIChasbeenmanuallyconfigured.Thiscausesduplex

inconsistencybetweentheswitchportandtheNIC.Symptomsincludepoorport

performanceandframe,checksequence(FCS)errorsthatincrementonthe

switchport.

Totroubleshootthisissue,trymanuallyconfiguringtheswitchportto100Mbps,

half-duplex.Ifthisactionresolvestheconnectivityproblems,youmayberunning

intothisNICissue.TryupdatingtothelatestdriversforyourNIC,orcontactyour

NICcardvendorforadditionalsupport.

擴(kuò)展ACL和標(biāo)準(zhǔn)ACL的區(qū)別(),

A.標(biāo)準(zhǔn)的ACL在禁止和允許方面比擴(kuò)展的ACL更高的精度

B.擴(kuò)展的ACL核查數(shù)據(jù)包的源地址和目標(biāo)地址和端口號

C他們都可以查端口號

D.他們都可以查特殊協(xié)議和其他參數(shù)

正確答案：B

StudytheExhibitbelowcarefully:

London#showvtp

VTPVersion:2

ConfigurationRevision:0

MaximumVLANssupportedlocally:64

NumberofexistingVLANs:5

VTPOperatingMode:Client

VTPDomainName:London

VTPPruningMode:Disabled

VTPV2Mode:Disabled

VTPTrapsGeneration