ccna考试题库.docx

1、ccna考试题库QUESTION37WhataretwocharacteristicsofRIPv2?(Choosetwo.)A.classfulroutingprotocolB.variable-lengthsubnetmasksC.broadcastaddressingD.manualroutesummarizationE.usesSPFalgorithmtocomputepathAnswer:BDExplanation/Reference:A：有类路由协议，错误B：可变长度子网掩码，正确C：采用广播地址更新，错误D：手动路由汇总，正确E:使用spf算法计算路径，错误。QUESTION38

2、WhichtwoEthernetfiber-opticmodessupportdistancesofgreaterthan550meters?A. 1000BASE-CXB.100BASE-FXC.1000BASE-LXD.1000BASE-SXE.1000BASE-ZXAnswer:CEExplanation/Reference:A：最长距离25米B：最长距离100米C：最长距离3000米D：最长距离550米E：最长距离70千米QUESTION39Whattwothingswillarouterdowhenrunningadistancevectorroutingprotocol?(Choo

3、setwo.)A.Sendperiodicupdatesregardlessoftopologychanges.B.Sendentireroutingtabletoallroutersintheroutingdomain.C.Usetheshortest-pathalgorithmtothedeterminebestpath.D.Updatetheroutingtablebasedonupdatesfromtheirneighbors.E.Maintainthetopologyoftheentirenetworkinitsdatabase.Answer:ADExplanation/Refere

4、nce:考点：考查距离矢量路由协议特性A：周期性更新，正确B：发送整个路由表到整个路由域，错误，只发送给邻居C：使用SPF算法，错误D：依靠邻居发送更新来更新路由表，正确E：在数据库中维护整个网络的拓扑。错误Whichcommandshowsifanaccesslistisassignedtoaninterface?A.showipinterfaceinterfaceaccess-listsB.showipaccess-listsinterfaceinterfaceC.showipinterfaceinterfaceD.showipaccess-listsinterfaceAnswer:CEx

5、planation/Reference:QUESTION42Refertotheexhibit.WhichruledoestheDHCPserverusewhenthereisanIPaddressconflict?A.Theaddressisremovedfromthepooluntiltheconflictisresolved.B.Theaddressremainsinthepooluntiltheconflictisresolved.C.OnlytheIPdetectedbyGratuitousARPisremovedfromthepool.D.OnlytheIPdetectedbyPi

6、ngisremovedfromthepool.E.TheIPwillbeshown,evenaftertheconflictisresolved.Answer:AExplanation/Reference:showipdhcpconflict命令可以查看哪些ip地址在使用上有冲突。有冲突的地址不再分配出去。A：地址被删除直到冲突解决，正确B:地址保留直到冲突解决，错误C/D：答案片面。E：当冲突解决后，地址会被显示。错误。QUESTION44Refertotheexhibit.Ifnumber2isselectedfromthesetupscript,whathappenswhentheuse

7、rrunssetupfromaprivilegedprompt?A.Setupisadditiveandanychangeswillbeaddedtotheconfigscript.B.Setupeffectivelystartstheconfigurationoverasiftherouterwasbootedforthefirsttime.C.Setupwillnotrunifanenablesecretpasswordexistsontherouter.D.Setupwillnotrun,becauseitisonlyviablewhennoconfigurationexistsonth

8、erouter.Answer:AExplanation/Reference:0不保存进入IOS命令配置模式1不保存返回设置模式2保存退出A：设置和改动被保存到配置脚本B：为有效地重新开始配置，如果路由器是第一次启动的配置。C：如果配置了密码，设置不会运行D：设置不可用，因为它只能在没有配置存在时才有效QUESTION49WhichtwostatementsdescribetheCiscoimplementationofVLANs?(Choosetwo.)A.VLAN1isthedefaultEthernetVLAN.B.CDPadvertisementsareonlysentonVLAN100

9、2.C.Bydefault,themanagementVLANisVLAN1005.D.Bydefault,theswitchIPaddressisinVLAN1005.E.VLAN1002through1005areautomaticallycreatedandcannotbedeleted.Answer:AEExplanation/Reference:考点：考查vlan知识点。A：缺省都存在vlan1，端口都属于vlan1，正确B：CDP信息只发送到vlan1002，错误，vlan1002是fddi网络的vlan号。C：缺省情况交换机IP配置在vlan1005，错误，vlan1005trn

10、et网络的vlan号。缺省在vlan1里面。D：vlan1002-1005自动生成并不能被删除，正确，他们都是被保留的特殊vlan。QUESTION56没有理解什么意思Refertotheexhibit.Whatdoesthe(*)representintheoutput?A.Packetisdestinedforalocalinterfacetotherouter.B.Packetwastranslated,butnoresponsewasreceivedfromthedistantdevice.C.Packetwasnottranslated,becausenoadditionalport

11、sareavailable.D.Packetwastranslatedandfastswitchedtothedestination.Answer:DExplanation/Reference:由图中提示信息可以看出，源为已经有个一个转换，所以后续的数据包快速转发。WhatarethreeadvantagesofVLANs?(Choosethree.)A.VLANsestablishbroadcastdomainsinswitchednetworks.B.VLANsutilizepacketfilteringtoenhancenetworksecurity.C.VLANsprovideamet

12、hodofconservingIPaddressesinlargenetworks.D.VLANsprovidealow-latencyinternetworkingalternativetoroutednetworks.E.VLANsallowaccesstonetworkservicesbasedondepartment,notphysicallocation.F.VLANscangreatlysimplifyadding,moving,orchanginghostsonthenetwork.Answer:AEFExplanation/Reference:A：VLAN在交换网络中建立广播域

13、，正确B：利用VLAN的数据包过滤，增强网络的安全性。错误，没有这个特性。C：提供了在大型网络中的保护IP地址的方法。错误D：提供低延迟互联网络替代路由网络。错误E：vlan允许基于逻辑划分的网络访问，不是物理位置。正确。F：VLAN可以大大简化添加，移动或更改网络上的主机。正确。QUESTION61AnadministratorwouldliketoconfigureaswitchoveravirtualterminalconnectionfromlocationsoutsideofthelocalLAN.Whichofthefollowingarerequiredinorderforthe

14、switchtobeconfiguredfromaremotelocation?(Choosetwo.)A.TheswitchmustbeconfiguredwithanIPaddress,subnetmask,anddefaultgateway.B.TheswitchmustbeconnectedtoarouteroveraVLANtrunk.C.TheswitchmustbereachablethroughaportconnectedtoitsmanagementVLAN.D.TheswitchconsoleportmustbeconnectedtotheEthernetLAN.E.The

15、switchmanagementVLANmustbecreatedandhaveamembershipofatleastoneswitchport.F.TheswitchmustbefullyconfiguredasanSNMPagent.Answer:ACExplanation/Reference:要想远程管理VLAN，1、交换机配置IP，2、路由可达QUESTION65WhichrouterIOScommandscanbeusedtotroubleshootLANconnectivityproblems?(Choosethree.)A.pingB.tracertC.ipconfigD.sh

16、owiprouteE.winipcfgF.showinterfacesAnswer:ADFExplanation/Reference:A：测试连通性D：查看是否有路由F：查看接口是否可用QUESTION64WhichofthefollowingarebenefitsofVLANs?(Choosethree.)A.Theyincreasethesizeofcollisiondomains.B.Theyallowlogicalgroupingofusersbyfunction.允许用户从逻辑上进行分组C.Theycanenhancenetworksecurity.D.Theyincreasethe

17、sizeofbroadcastdomainswhiledecreasingthenumberofcollisiondomains.E.Theyincreasethenumberofbroadcastdomainswhiledecreasingthesizeofthebroadcastdomains.F.Theysimplifyswitchadministration.Answer:BCEExplanation/Reference:考查VLAN的特点A：增加冲突域的大小，错误B：允许逻辑划分网段，正确C：增强网络安全，正确。不同vlan不能直接通信。D：当减少冲突域时增加广播域的大小。错误E：减

18、少广播域的大小时增加了广播域个数。正确。F:简化交换机管理。答非所问。QUESTION71Whichcharacteristicsarerepresentativeofalink-stateroutingprotocol?(Choosethree.)A.providescommonviewofentiretopologyB.exchangesroutingtableswithneighborsC.calculatesshortestpathD.utilizesevent-triggeredupdatesE.utilizesfrequentperiodicupdatesAnswer:ACDExp

19、lanation/Reference:链路状态路由协议有协议特点？A:提供查看拓扑的命令，正确。showipospfdatabaseB：邻居之间交换路由信息，错误。交换LSAC：计算最短路径，正确。D：利用触发更新，正确E：利用周期更新，错误。QUESTION73Usetheoutputfromtheroutershowninthegraphicabovetodeterminewhichofthefollowingarecorrect.(Choosetwo.)A.RouterJohnusesalink-stateroutingprotocol.B.RouterJohnwillreceivero

20、utingupdatesontheSerial0/0interface.C.RouterJohnwillreceiveroutingupdatesontheSerial0/1interface.D.RouterJohnwillsendroutingupdatesouttheSerial0/0interface.E.RouterJohnwillsendroutingupdatesouttheFastEthernet0/0interface.F.RouterJohnwillsendroutingupdatesouttheSerial0/1interface.Answer:BDExplanation

21、/Reference:由图中几处画红线的地方可知只有s0/0发送和接受路由信息。QUESTION742的次方问题AnationalretailchainneedstodesignanIPaddressingschemetosupportanationwidenetwork.Thecompanyneedsaminimumof300sub-networksandamaximumof50hostaddressespersubnet.WorkingwithonlyoneClassBaddress,whichofthefollowingsubnetmaskswillsupportanappropriat

22、eaddressingscheme?(Choosetwo.)A.B.C.D.E.F.Answer:BEExplanation/Reference:需要至少300个子网，每个子网至少50台主机。使用一个B类地址来划分。A：最多有256个子网，错误C：只有64个子网D：每个子网只有30个可用IPF：只有32个子网QUESTION79Whatinformationdoesarouterrunningalink-stateprotocolusetobuildandmaintainitstopologicaldatabase?(Choosetwo.)A.hellopacketsB.SAPmessages

23、sentbyotherroutersC.LSAsfromotherroutersD.beacons信息receivedonpoint-to-pointlinksE.routingtablesreceivedfromotherlink-stateroutersF.TTLpacketsfromdesignatedroutersAnswer:ACExplanation/Reference:链路状态路由协议如何维护拓扑数据库？A：hello包用于维护邻居关系，正确。B：错误，没有这个概念。C：通过其他路由器的LSA，正确。D：从点到点链路接收，错误。答案片面E：从其他路由器接收路由表，错误。相互间不直

24、接发送路由表。F：从DR接受TTL包，错误，答非所问。QUESTION80WhichstatementsdescribetheroutingprotocolOSPF?(Choosethree.)A.ItsupportsVLSM.B.Itisusedtoroutebetweenautonomoussystems.C.Itconfinesnetworkinstabilitytooneareaofthenetwork.D.Itincreasesroutingoverheadonthenetwork.E.Itallowsextensivecontrolofroutingupdates.F.Itissi

25、mplertoconfigurethanRIPv2.Answer:ACEExplanation/Reference:A：支持VLSM，正确B：在AS之间使用，错误。在AS内部使用C：限制了不稳定网络的范围，正确。通过划分区域实现。D：增加了网络的开销，错误。E：允许路由更新控制，正确。F：比RIPv2更容易配置，错误，答非所问。Whichofthefollowingaretypesofflowcontrol?(Choosethree.)A.bufferingB.cut-throughC.windowingD.congestionavoidanceE.loadbalancingAnswer:AC

26、DExplanation/Reference:流控制有哪些？A：缓存B：直通C：窗口机制D：拥塞避免E：负载均衡。Whatcanbedeterminedfromthelineofshowiprouteoutputshownintheexhibit?(Choosetwo.)注意R=rip管理距离修改RoutripDistance10A.Thenextroutingupdatecanbeexpectedin35seconds.B.TheIPaddressisconfiguredonS0/1.C.TheIPaddressisconfiguredonS0/1.D.Thisrouteisusingthe

27、defaultadministrativedistance.E.Thenetworkistwohopsawayfromthisrouter.Answer:DEExplanation/Reference:考点：考查RIP的路由条目。通过RIP学习到一条到达的路由，下一跳是，出接口是s/1。A：错误。rip更新周期为30s，正常计时器不会超过30B：错误，这个ip是对端接口ipC：错误。s0/1的ip无法得知D：正确，rip缺省的管理距离是120E：正确。QUESTION93Refertotheexhibit.FromRouterA,anetworkadministratorisabletopin

28、gtheserialinterfaceofRouterBbutunabletopinganyofthesubnetsattachedtoRouterB.Basedonthepartialoutputsintheexhibit,whatcouldbetheproblem?A.EIGRPdoesnotsupportVLSM.B.TheEIGRPnetworkstatementsareincorrectlyconfigured.C.TheIPaddressingontheserialinterfaceofRouterAisincorrect.D.Theroutingprotocolhassummar

29、izedontheclassfulboundary.E.EIGRPhasbeenconfiguredwithaninvalidautonomoussystemnumber.Answer:DQUESTION97ForwhattwopurposesdoestheEthernetprotocolusephysicaladdresses?(Choosetwo.)A.touniquelyidentifydevicesatLayer2B.toallowcommunicationwithdevicesonadifferentnetworkC.todifferentiateaLayer2framefromaL

30、ayer3packetD.toestablishaprioritysystemtodeterminewhichdevicegetstotransmitfirstE.toallowcommunicationbetweendifferentdevicesonthesamenetworkF.toallowdetectionofaremotedevicewhenitsphysicaladdressisunknownAnswer:AEExplanation/Reference:考点：考查mac地址的作用。A：在二层唯一确定一台设备，正确B：是设备在不同的网络中通信，错误，不同网络通信需要通过IP地址确定

31、。C：区别二层和三层帧，错误。D：确定设备的优先级，错误。没有这个功能。E：是同一网络的不同设备可以通信，正确F：当不知道远程设备的物理地址时可以查询，错误。不能跨网段。QUESTION98AsaframeleavesaLayer3device,theLayer2encapsulationinformationischangedfromwhatitwaswhenitenteredthedevice.Forwhattworeasonscanthishappen?(Choosetwo.)A.Thedataismovingfrom10BASE-TXto100BASE-TX.B.TheWANencapsulationtypehaschanged.C.Thedataformathaschangedfromanalogtodigital.D.Th