CCNA试题.docx

CCNA试题.docx

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CCNA试题

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（11）ListcommandstomonitorFrameRelayoperationontherouter

Intheusermodekeyinthefollowing:

Router>shoframe?

ipshowframerelayIPstatics

lmishowframerelaylmistatics

mapshowframerelaymaptable

pvcshowframerelaypvcstatics

routeshowframerelayroute

trafficshowframerelayprotocolstatics

（12）IdentifyPPPoperationstoencapsulateWANdataonCISCOrouters

PointtoPointProtocol（PPP）isadatalinkprotocolthatcanbeusedonasynchronous（dialup）orsynchronousISDNcircuits.ItusesLinkControlProtocol（LCP）tobuildandmaintaindatalinkconnections.SomefeaturesincludedinPPPare:

PasswordAuthenticationProtocol（PAP）andChallengeHandshakePasswordAuthenticationProtocol（CHAP）.DatacompressionandmultipleprotocolssuchasIP,IPX,AppleTalkDECnetandOSI/CLNSaresupported.EncapsulatePPPontherouter

#ints0

#encapsulateppp

（13）StatearelevantuseandcontextforISDNnetworking

IntegratedServicesDigitalNetwork（ISDN）canrunonexistingtelephoneslinestoprovideanendtoenddigitalserviceforbothdomesticandbusinessuses.ISDNcancarry,inadditiontovoiceanddata,multimediaaswell.ISDNcanusedasabackupcircuitforhighspeednetworklinks.CISCOrouterscanbeconfiguredtoautomaticallydialuponanISDNlinkwhenthemainnetworklinkgoesdown.

（14）IdentifyISDNprotocols,functiongroups,referencepointsandchannels

ISDNprotocolsweredefinedbyCCITT（nowITU-T）,andtherearethreeprotocolsthatdefinethecomplextransmissionissues:

∙ProtocolspecificationsbeginningwithlatterE,specifyISDNontheexistingtelephonenetwork,ie;Analoglines.

∙ProtocolspecificationsbeginningwithletterI,specifyconcepts,terminologyandservices.

∙ProtocolspecificationsbeginningwithletterQ,specifytrunkswitchingandsignaling.

（15）DescribeCisco’sImplementationofISDNBRI

ISDNBasicRateInterface（BRI）,serviceprovidestwoBchannelsandDchannel,whichisalsoknownas2B+D.Bchannelsoperateat64kbpsandcarriesuserinformationwhereDchanneloperatesat16kbpsandusuallycarrycontrolandsignalinginformation.DchannelsignalingprotocolspanstheOSIreferencemodels,Physicallayer,DatalinklayerandtheNetworklayer.Thetwo64kbpslinescanbeusedasasingle128kbpschannel.ToplaceacallonISDNissimilartoplacingacallonPlainOldTelephones（POTS）.ForISDNnetworktoidentifyacallplacedonitsnetwork,youmustusedirectorynumbersandServiceProfileIdentifiers（SPID）s.Thesetwoitemsaregiventoyoubytheserviceprovider.Directorynumberisatelephonenumberyouwillusewhenyoucall.TheSPIDisanumberthetelephoneusestoidentifyequipmentonyourISDNconnection.MajorityofswitchesinUSareeitherAT&T5ESS,4ESSorNorthernTelcomDMS100.AttachingaCISCOroutertoISDNneedseitheraNetworkTermination1oranISDNmodem.IfrouterhasaBRIinterface,（calledTerminalEndPoint1）thenitisreadytobeconnectedtotheISDNnetwork.

Router#configt

Router（config）#isdnswitch-typebasic-dms100

Router（config）#intbri0

Router（config-if）#encapppp

Router（config-if）#isdnspid775456721

Router（config-if）#pppauthenticationchap

IOS

（16）Logintoarouterinuserandprivilegemode

CISCOIOSsoftwarehasacommandinterpretercalledExec.Exechastwolevelsofaccess:

Usermodeandprivilegemode.Thesetwolevelsserveasforaccessintothedifferentlevelsofcommands.Inusermodeonecanonlydo:

Checkrouterstatus,connectingtoremotedevices,makingtemporarychangestoterminalsettingsandviewingbasicsysteminformation.Intheprivilegemodeyoucanchangetheconfigurationoftherouterandgetdetailreportsofrouterstatus.Testandrundebugoperations.Accessglobalconfigurationmodes.

Whenyoufirstlogintoarouter,pressENTERandyouwillbeintheExecmode.Atthepromptitwillaskifyouneedapassword.Router>ThisistheUsermodeasstatedaboveverylittlecanbedoneatthislevel.WhenyoutypeinEnable:

Router>Enableandpressreturnitwillaskforthepassword.Onceyoukeyinthecorrectpassword,yourintheprivilegemode.NowthepromptwillshowyouRouter#.

（17）Usethecontext-sensitivehelpfacility

Onecanreceivehelponanycommandbytyping?

afterthecommand.Inthefollowingexample:

Router#clock?

youtypedinclockaspaceandthequestionmark,andpressedenter.Replywasasfollows:

setSetthetimeanddate.Nowyouwanttoknowwhatformattoenter.Soyouputanotherquestionafterthesetasfollows:

Router#clockset?

.Nowyouwillgettheformatinthereplyasfollows:

hh:

mm:

ss:

CurrentTime（hh:

mm:

ss）

（18）Usethecommandhistoryandeditingfeatures

Theuserinterfacecomesinwithaneditingfeaturetohelpyoutypeinrepetitivecommands.Onecanturnoffeditingbytypingterminalnoeditingandagainturnitonbytypingterminalediting.

Therouterkeepsthelasttencommandsyouenteredduringyourconsoleorterminalsession,inaspecialmemorybuffercalledcommandhistory.Onecanrecallcommandsfromthecommandhistorybufferandreusethemormodifyslightlytosaveontyping.ToseeallthecommandstypethefollowingatthecommandpromptRouter#showhistoryandpressenter.Allcommandsyoutypedinwillbeshown.Toincreasethesizeofthecommandhistorybufferyoutypethefollowing:

Router#terminalhistorysize100.Thiswillincreasethesizeto100linesfromthedefaultvalue.VT100terminalemulationgivesuseofupdownandsidearrowsinadditiontotheotherkeysasshownbelow:

∙CTRL+AMovetothebeginningofthecommandline

∙CTRL+EMovetotheendofthecommandline

∙CTRL+F（orrightarrow）Moveonecharacterforward

∙CTRL+B（orleftarrow）Moveonecharacterbackward

∙CTRL+P（oruparrow）Repeatpreviouscommandentry

∙CTRL+N（ordownarrow）Mostrecentcommandrecall

∙ESC+BMovebackwardoneword

∙ESC+FMoveforwardoneword

（19）Examinerouterelements（RAM,ROM,CDP,show）

CISCOroutersusethefollowingtypeofmemory:

∙RandomAccessMemory（RAM）storestherunningconfigurationwhentherouterisrunninganditisclearedwhenswitchedoff.Alsoprovidescashing,routingtablesandpacketbuffering.TheIOSoperatesfromRAM

∙FlashMemoryisanelectricallyerasable,re-programmableROMthatholdstheoperatingsystemimageandmicrocode.Thisfacilitatestheupgradestotheoperatingsystemwithoutreplacingthechipsonthemotherboard.

∙ReadOnlyMemory（ROM）isusedbytheroutertostorebootstrapprogram,operationsystemsoftwareandPowerOnSelfTest（POST）.TheROMchipsareinstalledinsocketsontherouter’smotherboard,sothattheycanbereplacedorupgraded.ROMholdsthesmallerversionofIOSandisloadedduringpowerupsotheroutercanbootup.

∙NonvolatileRAM（NVRAM）Thismemorydoesnotlooseitsinformationwhentherouterispowereddown.Storesthesystemsstartupconfigurationfileandthevirtualconfigurationregister.

CiscoDiscoveryProtocol（CDP）isCisco’sproprietaryprotocolthatallowsyoutoaccessconfigurationonotherrouterswithasinglecommand.ByrunningSubNetworkAccessProtocol（SNAP）atthedatalinklayer,twodevicesrunningdifferentNetworkLayerprotocolscancommunicateandlearnabouteachother.ThesedevicesincludeallLANandsomeWANs.CDPstartsbydefaultonanyrouterversion1.3earlieranddiscoversneighboringCISCOroutersrunningCDPbydoingaDataLinkbroadcasts.Itdoesnotmatterwhatprotocolisrunningatthenetworklayer.OnceCDPhasdisprovedarouter,itcanthendisplayinformationabouttheupperlayerprotocols,suchasIPandIPX.TheroutercachestheinformationitreceivesfromitsCDPneighbors.AnytimearouterreceivesupdatedinformationthataCDPneighborhaschanged,itdiscardstheoldinformationinfavorofthebroadcast.

Therearemanyshowcommandsavailablefortheadministratortomanagetherouter.TheycanbefoundbytypingatthecommandpromptRouter#sh?

.

（20）Manageconfigurationfilesfromtheprivilegeexecmode.

Whentherouterispoweredup,itdoesaself-test,thenloadstheIOSimage,andfindstheconfigurationfileandloadsit.StartupconfigurationisinNVRAMandtheoperatingsystemplacesitontotheRAM.Tomanageconfigurationfilesyoumustbeinprivilegemode.Atstartupyouwillbeinusermode.Togettotheprivilegemodedothefollowing:

Router>enable,ifpasswordsareenabledthenenterthemwhenasked.Nowyourinprivilegemode.Router#.Bytypingconfigtyoucanmodifyconfigurationfiles.Followingarecommandsforstartingandsavingconfigurations:

∙Showstartup-configShowstheconfigurationthatwillloadedwhenthe

Routerboots.

∙Showrunning-configShowtheconfigurationthatiscurrentlyloaded

toRAMandisrunning

∙Erasestartup-configThiscommandwillerasetheconfigurationin

NVRAMandputyouintotheinitialconfigurationdialog

∙ReloadThiscommandwillreloadthestartup-configto

Memory

∙SetupThiscommandstartstheinitialconfigurationdialog

Softwareversion10.3andearliershouldrunthefollowingroutercommands:

∙ShowconfigSameasshowstartup-config

∙WritetermSameasshowrunning-config

∙WriteeraseSameaserasestartup-config

∙WritememSameascopyrunning-configstartupconfig

（21）Controlrouterpassword,identificationandbanner

TherearefivedifferentpasswordsthatisusedtosecureCISCOroutersandtheyareasfollows:

Enablesecretisacryptographicpasswordusedinversion10.3andup.Ithasprecedenceovertheenablepasswordwhenitexists.O