2021年度思科認(rèn)證考試題庫(kù)

CCNA640-802V13題庫(kù)試題分析題庫(kù)解說(shuō):吳教師(艾迪飛CCIE實(shí)驗(yàn)室首發(fā)網(wǎng)站:Whataretworeasonsthatanetworkadministratorwoulduseaccesslists?(Choosetwo.)tocontrolvtyaccessintoaroutertocontrolbroadcasttrafficthrougharoutertofiltertrafficasitpassesthrougharoutertofiltertrafficthatoriginatesfromtheroutertoreplacepasswordsasalineofdefenseagainstsecurityincursionsAnswer：AC解釋一下:在VTY線路下應(yīng)用ACL,可以控制從VTY線路進(jìn)來(lái)telnet流量。也可以過(guò)濾穿越一臺(tái)路由器流量。AdefaultFrameRelayWANisclassifiedaswhattypeofphysicalnetwork?point-to-pointbroadcastmulti-accessnonbroadcastmulti-accessnonbroadcastmultipointbroadcastpoint-to-multipointAnswer：C解釋一下:在默認(rèn)狀況ド,幀中繼為非廣播多路訪問(wèn)鏈路。但是也可以通過(guò)子接口來(lái)修改她網(wǎng)絡(luò)類型。Refertotheexhibit.Howmanybroadcastdomainsexistintheexhibitedtopology?A.oneB.twothreefourfivesixAnswer：C解釋一下:廣播域問(wèn)題,在默認(rèn)狀況下,每個(gè)互換機(jī)是不能隔離廣播域,因此在同一種區(qū)域所有互換機(jī)都在同一種廣播域中,但是為了減少?gòu)V播危害,將廣播限制在ー種更小范疇,有/VLAN概念，VLAN表達(dá)是ー種虛擬局域網(wǎng)，而她作用就是隔離廣播。因此被VLAN隔離了每個(gè)區(qū)域都表達(dá)ー種單獨(dú)廣播域，這樣ー種VLAN中廣播流量是不能傳到其她區(qū)域，因此在上題中就有3個(gè)廣播域J’。Asingle802.11gaccesspointhasbeenconfiguredandinstalledinthecenterofasquareoffice.Afewwirelessusersareexperiencingslowperformanceanddropswhilemostusersareoperatingatpeakefficiency.Whatarethreelikelycausesofthisproblem?(Choosethree.)mismatchedTKIPencryptionnullSSIDcordlessphonesmismatchedSSIDmetalfilecabinetsantennatypeordirectionAnswer：CEFThecommandframe-relaymapip102broadcastwasenteredontherouter.Whichofthefollowingstatementsistrueconcerningthiscommand?Thiscommandshouldbeexecutedfromtheglobalconfigurationmode.TheIPaddressisthelocalrouterportusedtoforwarddata.102istheremoteDLCIthatwillreceivetheinformation.ThiscommandisrequiredforallFrameRelayconfigurations.Thebroadcastoptionallowspackets,suchasRIPupdates,tobeforwardedacrossthePVC.Answer：E解釋一下：關(guān)于命令frame-relaymapip102broadcast,這個(gè)命令用于手工靜態(tài)添加一條映射,到達(dá)流量封裝ー種DLCI號(hào)為102,并且這條PVC是支持廣播流量,例如RIP更新包。由于在默認(rèn)狀況下,幀中繼網(wǎng)絡(luò)為非廣播,而R1P在其上是無(wú)法發(fā)包。8.WhichofthefollowingareassociatedwiththeapplicationlayeroftheOSImodel?(Choosetwo.)pingTelnetC.FTPD.TCPE.IPAnswer：BC解釋一下:在OSI7層模型中位于應(yīng)用層應(yīng)用有l(wèi)elnel和ftp這兩種應(yīng)用。Forsecurityreasons,thenetworkadministratorneedstopreventpingsintothecorporatenetworksfromhostsoutsidetheinternetwork.Whichprotocolshouldbeblockedwithaccesscontrollists?IPICMPC.TCPD.UDPAnswer：B解釋一下:PING命令運(yùn)用ICMP合同echo,和echo?replay兩個(gè)報(bào)文來(lái)檢測(cè)鏈路與否連通。因此如果要制止PING流量到網(wǎng)絡(luò),就只要過(guò)濾掉ICMP應(yīng)用就可以了。10.Refertotheexhibit.ThenetworkadministratorhascreatedanewVLANonSwitch1andaddedhostCandhostD.TheadministratorhasproperlyconfiguredswitchinterfacesFastEthemetO/13throughFastEthemetO/24tobemembersofthenewVLAN.However,afterthenetworkadministratorcompletedtheconfiguration,hostAcouldcommunicatewithhostB,buthostAcouldnotcommunicatewithhostCorhostD.Whichcommandsarerequiredtoresolvethisproblem?RouterItshoworoitfe5/245;24 51246124Router(config)#interfacefastethernet0/1.3Router(config-if)#encapsulationdotlq3Router(config-if)#ipaddressRouter(config)#routerripRouter(config-router)#networkRouter(config-router)#networkRouter(config-router)#networkSwitch1#vlandatabaseSwitchl(vlan)#vtpv2-modeSwitch1(vlan)#vtpdomainciscoSwitchl(vlan)#vtpserverSwitch1(config)#interfacefastethernet0/1Switch1(config-if)#switchportmodetrunkSwitch1(config-if)#switchporttrunkencapsulationislAnswer：A解釋一下:這是?種多VLAN間通訊問(wèn)題,雖然都同在一臺(tái)互換機(jī)上,但是由于處在不同VLAN中,而導(dǎo)致了不同VLAN中主機(jī)是不能通訊。這時(shí)咱們就需要借助與trunk和三層路由功能了，在互換機(jī)和路由器之間封裝TRUNK,這樣可以容許互換機(jī)間二層通訊,但是由于兩個(gè)VLAN是劃分到不同網(wǎng)段中，因而需要借助路由器路由功能來(lái)實(shí)現(xiàn)三層可達(dá)，可以將VLAN中主機(jī)網(wǎng)關(guān)指定為路由器與該VLAN相連子接口地址,這樣VLAN中數(shù)據(jù)包就都會(huì)發(fā)往網(wǎng)關(guān),而由網(wǎng)關(guān)來(lái)進(jìn)行進(jìn)一步轉(zhuǎn)發(fā)。在這個(gè)題中,題目給出了路由器子接口網(wǎng)段，而又給出了VLAN2與路由器相連接口IP地址,因此剩余ー種網(wǎng)段就是給VLAN3了,因此要在路由器上將與一種子接口劃分到VLAN3,并給其分派另ー種網(wǎng)段中IP地址。這樣就可以了。Whataretworecommendedwaysofprotectingnetworkdeviceconfigurationfilesfromoutsidenetworksecuritythreats?(Choosetwo.)AllowunrestrictedaccesstotheconsoleorVTYports.Useafirewalltorestrictaccessfromtheoutsidetothenetworkdevices.AlwaysuseTelnettoaccessthedevicecommandlinebecauseitsdataisautomaticallyencrypted.UseSSHoranotherencryptedandauthenticatedtransporttoaccessdeviceconfigurations.Preventthelossofpasswordsbydisablingpasswordencryption.Answer：BD解釋一下:要保證外部安全站點(diǎn)オ可以訪問(wèn)我網(wǎng)絡(luò),這就涉及到了安全問(wèn)題了,咱們可以使用防火墻來(lái)限制外網(wǎng)中來(lái)設(shè)備;也可以通過(guò)SSH或加密和認(rèn)證來(lái)控制。Refertotheexhibit.TheaccesslisthasbeenconfiguredontheS0/0interfaceofrouterRTBintheoutbounddirection.Whichtwopackets,ifroutedtotheinterface,willbedenied?(Choosetwo.)access-list101denytcp25anyeqtelnetaccess-list101permitipanyanyTelnelServersourceipaddress：；destinationport：21sourceipaddress:?7destinationport：21sourceipaddress:,1destinationport：21sourceipaddress:,6destinationport：23sourceipaddress：6；destinationport：23sourceipaddress:,9destinationport：23Answer：DE解釋一下:這個(gè)訪問(wèn)列表定義『兩個(gè)語(yǔ)句:access-list101denytcp25anyeqtelnetaccess-list101permitipanyany在訪問(wèn)列表中匹配順序是從上到下,如果匹配了某一句,就退出訪問(wèn)列表,如果沒(méi)有就始終往下匹配，在訪問(wèn)列表中有一句隱含回絕所有。因此不論怎么樣均有一句是能被匹配。在上題中，她定義第一句是回絕到從2-7發(fā)出任何telnet流量，然后第二句定義就是容許所有IP流量。并且要明確telnet流量使用是端口23,因此這個(gè)題答案就很明確了。Refertotheexhibit.Switch!hasjustbeenrestartedandhaspassedthePOSTroutine.HostAsendsitsinitialframetoHostC.Whatisthefirstthingtheswitchwilldoasregardspopulatingtheswitchingtable?HostBMAC-000A.8A47.E612 ム MAC-000B.DB95.2EE9IP- 導(dǎo) IP-2HostDSwitch1willaddtotheswitchingtable.Switch1willadd2totheswitchingtable.Switch1willadd000A.8A47.E612totheswitchingtable.Switch1willadd000B.DB95.2EE9totheswitchingtable.Answer：C解釋一下:互換機(jī)重新啟動(dòng)了，這個(gè)時(shí)候互換機(jī)MAC地址表是空,當(dāng)主機(jī)A發(fā)送數(shù)據(jù)給主機(jī)C而通過(guò)互換機(jī)時(shí),互換機(jī)依照她工作原理她要進(jìn)行原MAC地址學(xué)習(xí)，而由于對(duì)于這個(gè)目MAC地址無(wú)記錄，而將這個(gè)流量從除收到這個(gè)接口外所有接口泛洪出去。因此在最開(kāi)始ー步中，互換機(jī)是記錄下主機(jī)AMAC地址000A.8A47.E612到她MAC地址表中。heuserofHostlwantstopingtheDSLmodem/routerat54.BasedontheHostlARPtablethatisshownintheexhibit,whatwillHostldo?sendaunicastARPpackettotheDSLmodem/routersendunicastICMPpacketstotheDSLmodem/routersendLayer3broadcastpacketstowhichtheDSLmodem/routerrespondssendaLayer2broadcastthatisreceivedbyHost2,theswitch,andtheDSLmodem/routerAnswer：B解釋ー下:在下面表中咱們可以看到ARP表中關(guān)于于54ARP條目,因此在這主機(jī)都只需要發(fā)送單播ICMP包到DSLmodem/router即可〇Refertotheexhibit.WhatisthemostefficientsummarizationthatR1canusetoadvertiseitsnetworkstoR2?/24/2428/25/24/24/2428/25/24/22/21/22/24/24/24/24/2528/25/24/24/24Answer：C解釋一下:這還是ー種關(guān)于匯總問(wèn)題。規(guī)定R1將所有網(wǎng)段用匯總條目發(fā)送給R2,由于這些條目網(wǎng)絡(luò)位是相似都為172.1,因此在這需要匯總只是第3個(gè)八位,將4,4,5,6,7這些寫(xiě)成二進(jìn)制形式,然后找出相似位數(shù),則有相似位數(shù)字節(jié)就是她們掩碼位數(shù),而最小有相似位最小數(shù)字就是她們基數(shù)位,因此R1告示出去匯總條目為172.240/22。Refertotheexhibit.Assumethatallrouterinterfacesareoperationalandcorrectlyconfigured.Inaddition,assumethatOSPFhasbeencorrectlyconfiguredonrouterR2.HowwillthedefaultrouteconfiguredonRIaffecttheoperationofR2?A.AnypacketdestinedfbranetworkthatisnotdirectlyconnectedtorouterRIwillbedropped.AnypacketdestinedforanetworkthatisnotdirectlyconnectedtorouterR2willbedroppedimmediately.AnypacketdestinedforanetworkthatisnotdirectlyconnectedtorouterR2willbedroppedimmediatelybecauseofthelackofagatewayonRI.ThenetworksdirectlyconnectedtorouterR2willnotbeabletocommunicatewiththe,28,and4subnetworks.AnypacketdestinedforanetworkthatisnotreferencedintheroutingtableofrouterR2willbedirectedtoR1.R1willthensendthatpacketbacktoR2andaroutingloopwilloccur.Answer：E解釋一下:在RI上產(chǎn)生了一種OSPF缺省路由,出接口指定為S0/0,這條缺省路由以5類LSA形式告示給J'R2,于是R2上也有了一條標(biāo)記為〇?E/0出接口為SerialO/O路由。因此

R2收到任何路由表中沒(méi)有目網(wǎng)段時(shí),就將指定給R1,而RI依照缺省路山出接口又將數(shù)據(jù)包發(fā)往R2,這樣就形成了一種路由環(huán)路。Anetworkinterfaceporthascollisiondetectionandcarriersensingenabledonasharedtwistedpairnetwork.Fromthisstatement,whatisknownaboutthenetworkinterfaceport?Thisisa10Mb/sswitchport.Thisisa100Mb/sswitchport.C.rPhisisanEthernetportoperatingathalfduplex.ThisisanEthernetportoperatingatfullduplex.ThisisaportonanetworkinterfacecardinaPC.Answer：C解釋一下:一種接口有沖突檢測(cè)和載波偵聽(tīng),并且是使用雙絞線網(wǎng)絡(luò),那么對(duì)于這個(gè)接口咱們可以推測(cè)出她是以太接口,并且是工作在半雙工模式下。Refertothetopologyandrouterconfigurationshowninthegraphic.AhostontheLANisaccessinganFTPserveracrosstheInternet.Whichofthefollowingaddressescouldappearasasourceaddressforthepacketsforwardedbytheroutertothedestinationserver?TOC\o"1-5"\h\zinterfaceStriall ?1ipaddress20022.18256266256262 2~—Ipnatoutsidet <ヽInterfaceFastEthemetO SI：8/30ipaddress255^55255.0 fjQ10I〇〇］ハ4開(kāi)煙 Testinsideゆnatpooltest199999.40199593.62netmMk256255255224ゆnatInsidesourcelist1pooltestiprout?。。。〇00X)020022.17(acc?”粕11permit10.10000.0.0255A.B.C.3D.7E.7F.8Answer：D解釋一下:這是個(gè)NAT地址轉(zhuǎn)換題目,在這fi)/0接口連接下為私有地址,這些地址是不能同外網(wǎng)進(jìn)行通訊,這時(shí)就借助NAT,將內(nèi)網(wǎng)私有地址轉(zhuǎn)換為可以在公網(wǎng)上通訊地址,咱們看到NATPOOL中定義轉(zhuǎn)換后公有地址為0到2,則表達(dá)這段地址是我轉(zhuǎn)換后內(nèi)網(wǎng)全局地址，因此HOST想要穿過(guò)INTERNET訪問(wèn)FTP服務(wù)器,則需要轉(zhuǎn)換為公有地址0到2之內(nèi)地址，在上面答案中只有地址7滿足條件，因此答案就是D了。AcompanyisinstallingIPphones.Thephonesandofficecomputersconnecttothesamedevice.Toensuremaximumthroughputforthephonedata,thecompanyneedstomakesurethatthephonetrafficisonadifferentnetworkfromthatoftheofficecomputerdatatraffic.Whatisthebestnetworkdevicetowhichtodirectlyconnectthephonesandcomputers,andwhattechnologyshouldbeimplementedonthisdevice?(Choosetwo.)hubrouterswitchSTPsubinterfacesF.VLANAnswer：CF解釋一下:公司語(yǔ)音設(shè)備和辦公設(shè)備都連在相似設(shè)備上,還要保證語(yǔ)音數(shù)據(jù)流在不同與公司辦公數(shù)據(jù)流量,最佳網(wǎng)絡(luò)設(shè)備固然是互換機(jī)了,然后運(yùn)用VLAN技術(shù)就完全可以滿足所有規(guī)定了。22.Refertotheexhibit.WhichstatementdescribesDLCI17?A.DLCI17describestheISDNcircuitbetweenR2andR3.DLCI17describesaPVConR2.ItcannotbeusedonR3orR1.DLCI17istheLayer2addressusedbyR2todescribeaPVCtoR3.DLCI17describesthedial-upcircuitfromR2andR3totheserviceprovider.Answer：C解釋?下：DLCI是在Frame-relay中描述二層信息地址,她地位等同于以太網(wǎng)中MAC地址。咱們以R2上DLCI17來(lái)看,DLCI17描述是:從這個(gè)接口出去目地為R3接口這條PVC二層地址為17。Whichroutingprotocolbydefaultusesbandwidthanddelayasmetrics?A.RIPB.BGPC.OSPFD.EIGRPAnswer：D解釋一下:在咱們路由合同中使用復(fù)合度量合同只有IGP和EIGPR,而她們?cè)谀J(rèn)狀況下是使用帶寬和延時(shí)來(lái)計(jì)算度量。IntheimplementationofVLSMtechniquesonanetworkusingasingleClassCIPaddress,whichsubnetmaskisthemostefficientforpoint-to-pointseriallinks?A.B.40C.48D.52E.54Answer：D解釋ー下:在點(diǎn)到點(diǎn)鏈路上由于只需要分派兩個(gè)地址給兩端就可以J’,因此加上網(wǎng)絡(luò)地址和廣播地址,這個(gè)網(wǎng)段也就只需要有4個(gè)地址了,因此網(wǎng)絡(luò)位需要匹配30位,掩碼就為52.Refertotheexhibit.ThenetworksconnectedtorouterR2havebeensummarizedasa/21routeandsenttoRI.WhichtwopacketdestinationaddresseswillRIforwardtoR2?(Choosetwo.)OtherOtherNetworksA.60B.1C.D.55E.F.5Answer：BE解釋一下:這個(gè)題其實(shí)就是考察匯總問(wèn)題,她說(shuō)意思是R2發(fā)送了一種匯總路由/21給R1,哪兩個(gè)包文目地R1仍將轉(zhuǎn)發(fā)給R2。這還是匯總問(wèn)題ー種反向考察,依照21位掩碼位數(shù)可以推斷在第3個(gè)八位字節(jié)前5位是相似,不同是背面3位，而將176寫(xiě)成二進(jìn)制形式為10110000,因此可以看出來(lái)明細(xì)路由可以是176-183,因此在上面答案中可以很容易看到答案B和E是咱們明細(xì)路由。Refertotheexhibit.Switch-1needstosenddatatoahostwithaMACaddressof00b0,d056.efa4.WhatwillSwitch-1dowiththisdata?Switch-1#showmacaddress-tableTOC\o"1-5"\h\zDynamicAddressesCount 3SecureAddresses(User-defined)Count 0StaticAddresses(User-defined)Count 0SystemSelfAddressesCount 41TotalMad/卻鱒羋s 156ユNon-staticAtidrSss wCDestinationAddressAddressTypeVLANDestinationPort0010OdeOe289 Dynamic 1 FastEttiemetO/100107b001540 Dynamic 2 FastEthernetO/300107boe1,1545 Dynamic 2 FastEthemetO/2Switch-1willdropthedatabecauseitdoesnothaveanentryforthatMACaddress.Switch-1willfloodthedataoutallofitsportsexcepttheportfromwhichthedataoriginated.Switch-1willsendanARPrequestoutallitsportsexcepttheportfromwhichthedataoriginated.Switch-1willforwardthedatatoitsdefaultgateway.Answer：B解釋一下:一方面Switch1需要發(fā)送?種數(shù)據(jù)到MAC地址為00b0.d056.efa4主機(jī),理解到目地后,就查看她MAC地址表,然后發(fā)當(dāng)前MAC地址表中沒(méi)有這個(gè)MAC地址條目存在。互換機(jī)在收到未知單播,組播和廣播時(shí),都采用是泛洪方式,往除收到數(shù)據(jù)這個(gè)接口外所有接口都發(fā)送。因此在這兒,Switch1也采用上泛洪方式。woroutersnamedAtlantaandBrevardareconnectedbytheirserialinterfacesasshownintheexhibit,butthereisnodataconnectivitybetweenthem.TheAtlantarouterisknowntohaveacorrectconfiguration.Giventhepartialconfigurationsshownintheexhibit,whatistheproblemontheBrevardrouterthatiscausingthelackofconnectivity?

AtlantaBrevardAtlanla^showintertacesMSerialOisupfAtlantaBrevardAtlanla^showintertacesMSerialOisupflineprotocolisupHaidwdreisHD6457Qレ’0??Internetaddressis/24MTU1500bytes.BW1544Kbitreliablity255.255EncapsulationHDLC,loopbacknotsetKeepaliveset(10sec)Brevardflshowinterfacess1S?riatlisup.ineprotocolisupHm小?ioRHM4570InternetaddressH/24MTU1500bytes,BW56000Kbit.reliability255/255Enc4ip?iilationHDLC,loopbacknotsetKeepaliveset(10sec)Aloopbackisnotset.TheIPaddressisincorrect.Thesubnetmaskisincorrect.Theseriallineencapsulationsareincompatible.E.rrhemaximumtransmissionunit(MTU)sizeistoolarge.F.Thebandwidthsettingisincompatiblewiththeconnectedinterface.Answer：B解釋一下:很明顯錯(cuò)誤啊,兩臺(tái)路由器串行接口地址配備錯(cuò)誤,不是在相似網(wǎng)段,從而導(dǎo)致了不能通訊。WhichtwovaluesareusedbySpanningTreeProtocoltoelectarootbridge?(Choosetwo.)amountofRAMbridgepriorityIOSversionIPaddressMACaddressspeedofthelinksAnswer：BE解釋一下:生成樹(shù)選舉問(wèn)題,根橋選舉是通過(guò)比較BID,而B(niǎo)ID由橋優(yōu)先級(jí)和MAC地址構(gòu)成.因此在選根橋時(shí)候需要比較是橋優(yōu)先級(jí)和MACaddressoRefertotheexhibit.Whichswitchprovidesthespanning-treedesignatedportroleforthenetworksegmentthatservicestheprinters?Switchl DistributionLay?r Switch?PiiiiteisPfiority4096：Switchl DistributionLay?r Switch?PiiiiteisPfiority4096：0010Jbcc.7320Piioiity32768MAC0010.7bcc.7347Piioiity8192MAC0010.7bcc.732dSwitch)aMPiioiity32768 ,MAC0010.7bcc.733aSwitch1Switch2Switch3Switch4Answer：C解釋一下:這是個(gè)關(guān)于生成樹(shù)選舉問(wèn)題,咱們ー方面需要找到根橋,而根橋選舉是通過(guò)比較橋ID,并且是越小越優(yōu)先,橋ID構(gòu)成為橋優(yōu)先級(jí)和MAC地址。因此咱們通過(guò)上圖可以找到根橋?yàn)閟witch1〇然后在非根橋上選出根端口,通過(guò)比較到根橋耗費(fèi)來(lái)選舉,耗費(fèi)最小就是根端口。由于上圖中沒(méi)有表達(dá)出鏈路帶寬,因此無(wú)法比較她們耗費(fèi)。下ー步咱們來(lái)選舉指派端口。每條鏈路都需要有一種DP,先是比較耗費(fèi),如果耗費(fèi)相似則比較BID（橋優(yōu)先級(jí)）,仍是越小越優(yōu)先,依照上圖表識(shí),咱們可以找到每條鏈路上DP,而連Printers鏈路上DP就為Switch3,由于她有更小MAC地址。32.Refertotheexhibit.WhywouldthenetworkadministratorconfigureRAinthismanner?F?A(corYflg)#accessdist2permit55RA(conflg)/linevty04RA(con1ig-line)tfaccess-class2intogivestudentsaccesstotheInternettopreventstudentsfromaccessingthecommandpromptofRAtopreventadministratorsfromaccessingtheconsoleofRAtogiveadministratorsaccesstotheInternettopreventstudentsfromaccessingtheInternettopreventstudentsfromaccessingtheAdminnetworkAnswer：B解釋一下:在這兒,將ACL應(yīng)用到VTY線路下,并且是IN方向,表達(dá)凡是被我ACL容許オ干lelnet到我.在RA上配備是permit55依照隱式denyany容許Admin網(wǎng)段中顧客可以記Inel到她,因此Swdcnl網(wǎng)段中顧客是被回絕.InordertoallowtheestablishmentofaTelnetsessionwitharouter,whichsetofcommandsmustbeconfigured?router(config)#lineconsole0router(config-line)#enablepasswordciscorouter(config)#lineconsole0router(config-line)#enablesecretciscorouter(config-line)#loginrouter(config)#lineconsole0router(config-line)#passwordciscorouter(config-line)#loginrouter(config)#linevty0router(config-line)#enablepasswordciscorouter(config)#linevty0router(config-line)#enablesecretciscorouter(config-line)#loginrouter(config)#linevty0router(config-line)#passwordciscorouter(config-line)#login解釋一下:⑹nel是ー種應(yīng)用層應(yīng)用,她使用是vty線路,并且在默認(rèn)狀況下,是需要訪問(wèn)線路下設(shè)有密碼。而在VTY線路下設(shè)立密碼命令為passworks府〃g,而VTY線路下另ー種命令login則是默認(rèn),可寫(xiě)也可不寫(xiě)。如果想Telnet時(shí)在VTY線路下不設(shè)立密碼也可以訪問(wèn)這個(gè)線路,可以在該VTY線路下輸入命令nologin〇Refertotheexhibit.ThetwoexhibiteddevicesaretheonlyCiscodevicesonthenetwork.Theserialnetworkbetweenthetwodeviceshasamaskof52.Giventheoutputthatisshown,whatthreestatementsaretrueofthesedevices?(Choosethree.)HanchesS”sh'cdpeatry? 1-—… 貝支|nvndaDeviceID:LondバアZ^^^^Entryaddress(es):IPaddress:PlatforB：cisco2610,Capabilities:RouterIntelface:Serial10/0#PortID(outgoingport):SerlalO/1Holdtme:125sec<cucpucA.TheManchesterserialaddressis.B.TheManchesterserialaddressis.C.rrheLondonrouterisaCisco2610.TheManchesterrouterisaCisco2610.TheCDPinformationwasreceivedonportSerial0/0oftheManchesterrouter.TheCDPinformationwassentbyportSerial0/0oftheLondonrouter.解釋一下:CDP是CISC0私有一種二層合同,但是她卻可以發(fā)現(xiàn)三層IP信息,通過(guò)CDP可以發(fā)現(xiàn)鄰居信息有:設(shè)備名稱,IP地址,端口,能力,平臺(tái),對(duì)端holddowntime.在上圖showcdpentry?命令顯示可以看到信息有:設(shè)備名稱:London；IP地址:；平臺(tái):cisco2610；能力:Router；端口:s0/1；holdtime：125S.Manchesteter收到這個(gè)CDP信息接口為S0/0.綜合一下,這個(gè)題目答案就出來(lái)了.Anetworkadministratorhasconfiguredtwoswitches,namedLondonandMadrid,touseVTP.However,theswitchesarenotsharingVTPmessages.Giventhecommandoutputshowninthegraphic,whyaretheseswitchesnotsharingVTPmessages?1011*2sh?wvty>statusMadrids vt|istatusVTPVtnion:2VTPVmioti:2CtnigurationRation:0ConCguratxnRevKion:?MaximumVLAMs bcelly:64MaximamVLANssupportedlocallyNumberメ?xi的nqVLAN><y:5NunibtrofexMpgVLANt:SVTPOptfNoqMak：SwvtrVTPOHan.：LondonVTPDomaknflattw：MadridVTPPruningMode:DIsaModVTPPnifiln9Mode：OiBbledVTPV2Mole;DgbQdVTPV?;D&bl貝VTPTrap^G9neotionVTPTrap*G，ロ9：DisabledTheVTPversionisnotcorrectlyconfigured.TheVTPoperatingmodeisnotcorrectlyconfigured.TheVTPdomainnameisnotcorrectlyconfigured.VTPpruningmodeisdisabled.VTPV2modeisdisabled.VTPtrapsgenerationisdisabled.Answer：C解釋一下:互換機(jī)間不能共享VTP信息,咱們就需要檢查VTP狀態(tài),一方面需要檢查是VTP域名,只有同一種域中オ也許互相學(xué)習(xí),再來(lái)檢查VTP模式,必要有一種server模式オ干有VTP學(xué)習(xí)過(guò)程,默認(rèn)狀況下VTP模式為Server。然后咱們檢查圖題目給出信息,可以看到兩臺(tái)互換機(jī)VTPdomain是不一致，因此這個(gè)就是問(wèn)題所在Host1istryingtocommunicatewithHost2.TheeOinterfaceonRouterCisdown.Whichofthefollowingaretrue?(Choosetwo.)RouterCwilluseICMPtoinformHost1thatHost2cannotbereached.RouterCwilluseICMPtoinformRouterBthatHost2cannotbereached.RouterCwilluseICMPtoinformHost1,RouterA,andRouterBthatHost2cannotbereached.RouterCwillsendaDestinationUnreachablemessagetype.RouterCwillsendaRouterSelectionmessagetype.RouterCwillsendaSourceQuenchmessagetype.Answer：AD解釋一下:連Host2接UEO/Odownj',那么最直接反映就發(fā)生在路由器C上，C路由表中這個(gè)條目就消失了,因而當(dāng)Host1想要跟Host2建立連接時(shí)候,RouterC就發(fā)送ー種目網(wǎng)段不可達(dá)消息:如果是使用ping命令，那么RouterC就使用ICMP包文告訴Host1,Host2是不可打。Refertotheexhibit.Assumingthattherouterisconfiguredwiththedefaultsettings,whattypeofrouterinterfaceisthis?R!和howinieifacef?outpiiomitted??outputomitted?is呼,LneprotocolisupHardwaic券Lxuice.adchtssis001Q^b80bfo6(bia0pl0.7bS0bfa6)MTU BWJOWQDKbit.t'LYWw淪 2T3,Hd1/255Enc&psulahoQARFA,loopbacksotset.keepdiveset(10tec)ARPtypeAFPA.XPPlimeout"OT0O.O(f?oulpntEthernetFastEthemetGigabitEthernetasynchronousserialsynchronousserialAnswer：B解釋?下:這個(gè)題是需要依照?qǐng)D中提供信息來(lái)判斷接口類型。可以看到接口MAC地址,表達(dá)這個(gè)接口必定不是串行接口,因此可以排除D和E選項(xiàng)?？磶払W100000Kbit,表達(dá)是100M帶寬,因此這是個(gè)FastEthernet接口。Onpoint-to-pointnetworks,OSPFhellopacketsareaddressedtowhichaddress?A.B.C.D.E.F.55Answer：E解釋一下:在OSPF中Hello包發(fā)向是和這兩個(gè)地址。人們?cè)谧鯫SPF實(shí)驗(yàn)時(shí)候,用debug命令是可以看到這兩個(gè)個(gè)地址。Whiletroubleshootingaconnectivityproblem,anetworkadministratornoticesthataportstatusLEDonaCiscoCatalystseriesswitchisalternatinggreenandamber.Whichconditioncouldthisindicate?Theportisexperiencingerrors.Theportisadministrativelydisabled.Theportisblockedbyspanningtree.Theporthasanactivelinkwithnormaltrafficactivity.Answer：A解釋一下:CISCO互換機(jī)端n狀態(tài)批示燈是閃爍綠色和淺黃色,表達(dá)端口有操作問(wèn)題——也許是過(guò)量錯(cuò)誤或連接問(wèn)題。Refertotheexhibit.ThenetworkshownintheexhibitisrunningtheRIPv2routingprotocol.Thenetworkhasconverged,andtheroutersinthisnetworkarefunctioningproperly.TheFastEthernetO/OinterfaceonRIgoesdown.Inwhichtwowayswilltheroutersinthisnetworkrespondtothischange?(Choosetwo.)A.Allrouterswillreferencetheirtopologydatabasetodetermineifanybackuproutestothenetworkareknown.RoutersR2andR3marktherouteasinaccessibleandwillnotacceptanyfurtherroutingupdatesfromR1untiltheirhold-downtimersexpire.Becauseofthesplit-horizonrule,routerR2willbepreventedfromsendingerroneousinformationtoR1aboutconnectivitytothenetwork.WhenrouterR2learnsfromRIthatthelinktothenetworkhasbeenlost,R2willrespondbysendingaroutebacktoRIwithaninfinitemetrictothenetwork.RIwillsendLSAstoR2andR3informingthemofthischange,andthenallrouterswillsendperiodicupdatesatanincreasedrateuntilthenetworkagainconverges.Answer：CD解釋一下:這涉及到RIP關(guān)于環(huán)路避免幾種機(jī)制了。在這里RI直連鏈路發(fā)生了變化,及時(shí)觸發(fā)更新（觸發(fā)更新）,發(fā)送flashupdate出去,將這個(gè)條目置為possibledown,設(shè)立最大跳數(shù)（路由毒性），R2收到這個(gè)flashupdate后,也回答一種flashupdate包（毒性逆轉(zhuǎn)）,同步將這個(gè)條目也置為possibledown?設(shè)立最大跳數(shù)。WhichofthefollowingdescribetheprocessidentifierthatisusedtorunOSPFonarouter?（Choosetwo.）It