ExamA

QUESTION1

Refertotheexhibit.

BasedonthisFIBtable,whichstatementiscorrect?

Thereisnodefaultgateway.

TheIPaddressoftherouteronFastEthernetis.

Thegatewayoflastresortis.

Therouterwilllistenforallmulticasttraffic.

CorrectAnswer:CSection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:

The/0routeisthedefaultrouteandislistedasthefirstCEFentry.Hereweseethenexthopforthisdefaultroutelistsasthedefaultrouter

(gatewayoflastresort).

QUESTION2

Refertotheexhibit.

Anetworkadministratorchecksthisadjacencytableonarouter.Whatisapossiblecausefortheincompletemarking?

incompleteARPinformation

incorrectACL

dynamicroutingprotocolfailure

seriallinkcongestion

CorrectAnswer:A

Section:(none)

Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:

TodisplayinformationabouttheCiscoExpressForwardingadjacencytableorthehardwareLayer3-switchingadjacencytable,usetheshowadjacencycommand.

ReasonsforIncompleteAdjacencies

Therearetwoknownreasonsforanincompleteadjacency:

TheroutercannotuseARPsuccessfullyforthenext-hopinterface.

Afteracleariparporaclearadjacencycommand,theroutermarkstheadjacencyasincomplete.Thenitfailstocleartheentry.

InanMPLSenvironment,IPCEFshouldbeenabeledforLabelSwitching.Interfacelevelcommandiproute-cachecefNoARPEntryWhenCEFcannotlocateavalidadjacencyforadestinationprefix,itpuntsthepacketstotheCPUforARPresolutionand,inturn,forcompletionoftheadjacency.

Reference:

/c/en/us/support/docs/ip/express-forwarding-cef/17812-cef-

incomp.html#t4

QUESTION3

AnetworkengineernoticesthattransmissionratesofsendersofTCPtrafficsharplyincreaseanddecreasesimultaneouslyduringperiodsofcongestion.Whichconditioncausesthis?

globalsynchronization

taildrop

randomearlydetection

queuemanagementalgorithm

CorrectAnswer:ASection:(none)Explanation

Explanation/Reference:

TCPglobalsynchronizationincomputernetworkscanhappentoTCP/IPflowsduringperiodsofcongestionbecauseeachsenderwillreducetheirtransmissionrateatthesametimewhenpacketlossoccurs.RoutersontheInternetnormallyhavepacketqueues,toallowthemtoholdpacketswhenthenetworkisbusy,ratherthandiscardingthem.Becauseroutershavelimitedresources,thesizeofthesequeuesisalsolimited.Thesimplesttechniquetolimitqueuesizeisknownastaildrop.Thequeueisallowedtofilltoitsmaximumsize,andthenanynewpacketsaresimplydiscarded,untilthereisspaceinthequeueagain.ThiscausesproblemswhenusedonTCP/IProutershandlingmultipleTCPstreams,especiallywhenburstytrafficispresent.Whilethenetworkisstable,thequeueisconstantlyfull,andtherearenoproblemsexceptthatthefullqueueresultsinhighlatency.However,theintroductionofasuddenburstoftrafficmaycauselargenumbersofestablished,steadystreamstolosepacketssimultaneously.

Reference:

/wiki/TCP_global_synchronization

QUESTION4

WhichthreeproblemsresultfromapplicationmixingofUDPandTCPstreamswithinanetworkwithnoQoS?(Choosethree.)

starvation

jitter

latency

windowing

lowerthroughput

CorrectAnswer:ACESection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:ItisageneralbestpracticenottomixTCP-basedtrafficwithUDP-basedtraffic(especiallystreamingvideo)withinasingleserviceproviderclassduetothebehaviorsoftheseprotocolsduringperiodsofcongestion.Specifically,TCPtransmitterswillthrottle-backflowswhendropshavebeendetected.AlthoughsomeUDPapplicationshaveapplication-levelwindowing,flowcontrol,andretransmissioncapabilities,mostUDPtransmittersarecompletelyoblivioustodropsandthusneverlowertransmissionratesduetodropping.WhenTCPflowsarecombinedwithUDPflowsinasingleserviceproviderclassandtheclassexperiencescongestion,thenTCPflowswillcontinuallylowertheirrates,potentiallygivinguptheirbandwidthtodrop-obliviousUDPflows.ThiseffectiscalledTCP-starvation/UDP-dominance.Thiscanincreaselatencyandlowertheoverallthroughput.TCP-starvation/UDP-dominancelikelyoccursif(TCP-based)mission-criticaldataisassignedtothesameserviceproviderclassas(UDP-based)streamingvideoandtheclassexperiencessustainedcongestion.EvenifWREDisenabledontheserviceproviderclass,thesamebehaviorwouldbeobserved,asWRED(forthemostpart)onlyaffectsTCP-basedflows.Granted,itisnotalwayspossibletoseparateTCP-basedflowsfromUDP-basedflows,butitisbeneficialtobeawareofthisbehaviorwhenmakingsuchapplication-mixingdecisions.Reference:

/warp/public/cc/so/neso/vpn/vpnsp/spqsd_wp.htm

QUESTION5

WhichmethodallowsIPv4andIPv6toworktogetherwithoutrequiringbothtobeusedforasingleconnectionduringthemigrationprocess?

dual-stackmethod

6to4tunneling

GREtunneling

NAT-PT

CorrectAnswer:ASection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:

DualstackmeansthatdevicesareabletorunIPv4andIPv6inparallel.ItallowshoststosimultaneouslyreachIPv4andIPv6content,soitoffersaveryflexible

coexistencestrategy.ForsessionsthatsupportIPv6,IPv6isusedonadualstackendpoint.IfbothendpointssupportIPv4only,thenIPv4isused.

Benefits:

NativedualstackdoesnotrequireanytunnelingmechanismsoninternalnetworksBothIPv4andIPv6runindependentofeachother

Dualstacksupportsgradualmigrationofendpoints,networks,andapplications.Reference:http://

/web/strategy/docs/gov/IPV6at_a_glance_c45-625859.pdf

QUESTION6

WhichstatementabouttheuseoftunnelingtomigratetoIPv6istrue?

Tunnelingislesssecurethandualstackortranslation.

Tunnelingismoredifficulttoconfigurethandualstackortranslation.

Tunnelingdoesnotenableusersofthenewprotocoltocommunicatewithusersoftheoldprotocolwithoutdual-stackhosts.

TunnelingdestinationsaremanuallydeterminedbytheIPv4addressinthelow-order32bitsofIPv4-compatibleIPv6addresses.

CorrectAnswer:CSection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:

Usingthetunnelingoption,organizationsbuildanoverlaynetworkthattunnelsoneprotocolovertheotherbyencapsulatingIPv6packetswithinIPv4packetsand

IPv4packetswithinIPv6packets.Theadvantageofthisapproachisthatthenewprotocolcanworkwithoutdisturbingtheoldprotocol,thusprovidingconnectivity

betweenusersofthenewprotocol.Tunnelinghastwodisadvantages,asdiscussedinRFC6144:

Usersofthenewarchitecturecannotusetheservicesoftheunderlyinginfrastructure.

Tunnelingdoesnotenableusersofthenewprotocoltocommunicatewithusersoftheoldprotocolwithoutdual-stackhosts,whichnegatesinteroperability.Reference:

/c/en/us/

products/collateral/ios-nx-os-software/enterprise-ipv6-solution/white_paper_c11-676278.html

QUESTION7

Anetworkadministratorexecutesthecommandcleariproute.Whichtwotablesdoesthiscommandclearandrebuild?(Choosetwo.)

IProuting

FIB

ARPcache

MACaddresstable

CiscoExpressForwardingtable

topologytable

CorrectAnswer:ABSection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:

ToclearoneormoreentriesintheIProutingtable,usethefollowingcommandsinanymode:

CommandPurposecleariproute{*|

Clearsoneormoreroutesfromboththe

{route|

unicastRIBandallthemoduleFIBs.Theprefix/length}[next-hoprouteoptionsareasfollows:

interface]}

*--Allroutes.[vrfvrf-name]Example:

route--AnindividualIProute.switch(config)#clearip

prefix/length--AnyIPprefix.route

·next-hop--Thenext-hopaddress·interface--Theinterfacetoreachthenext-hopaddress.Thevrf-namecanbeanycase-sensitive,al-phanumericstringupto32characters.

Reference:

/c/en/us/td/docs/switches/datacenter/nexus5000/sw/unicast/5_0_3_N1_1/Ci

sco_n5k_layer3_ucast_cfg_rel_503_N1_1/l3_manage-routes.html

QUESTION8

Whichswitchingmethodisusedwhenentriesarepresentintheoutputofthecommandshowipcache?

fastswitching

processswitching

CiscoExpressForwardingswitching

cut-throughpacketswitching

CorrectAnswer:ASection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:

Fastswitchingallowshigherthroughputbyswitchingapacketusingacachecreatedbytheinitialpacketsenttoaparticulardestination.Destinationaddressesare

storedinthehigh-speedcachetoexpediteforwarding.Routersofferbetterpacket-transferperformancewhenfastswitchingisenabled.Fastswitchingisenabled

bydefaultonallinterfacesthatsupportfastswitching.

TodisplaytheroutingtablecacheusedtofastswitchIPtraffic,usethe"showipcache"EXECcommand.Reference:

/c/en/us/td/docs/ios/12_2/switch/command/reference/fswtch_r/xrfscmd5.ht

ml#wp1038133

QUESTION9

Whichtwoactionsmustyouperformtoenableandusewindowscalingonarouter?(Choosetwo.)

Executethecommandiptcpwindow-size65536.

Setwindowscalingtobeusedontheremotehost.

Executethecommandiptcpqueuemax.

SetTCPoptionsto"enabled"ontheremotehost.

Executethecommandiptcpadjust-mss.

CorrectAnswer:ABSection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:TheTCPWindowScalingfeatureaddssupportfortheWindowScalingoptioninRFC1323,TCPExtensionsforHighPerformance.AlargerwindowsizeisrecommendedtoimproveTCPperformanceinnetworkpathswithlargebandwidth-delayproductcharacteristicsthatarecalledLongFatNetworks(LFNs).TheTCPWindowScalingenhancementprovidesthatsupport.ThewindowscalingextensioninCiscoIOSsoftwareexpandsthedefinitionoftheTCPwindowto32bitsandthenusesascalefactortocarrythis32-bitvalueinthe16-bitwindowfieldoftheTCPheader.Thewindowsizecanincreasetoascalefactorof14.Typicalapplicationsuseascalefactorof3whendeployedinLFNs.TheTCPWindowScalingfeaturecomplieswithRFC1323.ThelargerscalablewindowsizewillallowTCPtoperformbetteroverLFNs.Usetheiptcpwindow-sizecommandinglobalconfigurationmodetoconfiguretheTCPwindowsize.Inorderforthistowork,theremotehostmustalsosupportthisfeatureanditswindowsizemustbeincreased.Reference:

/c/en/us/td/docs/ios-xml/ios/ipapp/

configuration/12-4t/iap-12-4t-book/iap-tcp.html#GUID-BD998AC6-F128-47DD-B5F7-B226546D4B08

QUESTION10

WhichthreeTCPenhancementscanbeusedwithTCPselectiveacknowledgments?(Choosethree.)

headercompression

explicitcongestionnotification

keepalive

timestamps

TCPpathdiscovery

MTUwindow

CorrectAnswer:BCDSection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:

TCPSelectiveAcknowledgment

TheTCPSelectiveAcknowledgmentfeatureimprovesperformanceifmultiplepacketsarelostfromoneTCPwindowofdata.

Priortothisfeature,becauseoflimitedinformationavailablefromcumulativeacknowledgments,aTCPsendercouldlearnaboutonlyonelostpacketper-round-trip

time.Anaggressivesendercouldchoosetoresendpacketsearly,butsuchre-sentsegmentsmighthavealreadybeensuccessfullyreceived.

TheTCPselectiveacknowledgmentmechanismhelpsimproveperformance.ThereceivingTCPhostreturnsselectiveacknowledgmentpacketstothesender,

informingthesenderofdatathathasbeenreceived.Inotherwords,thereceivercanacknowledgepacketsreceivedoutoforder.Thesendercanthenresendonly

missingdatasegments(insteadofeverythingsincethefirstmissingpacket).

Priortoselectiveacknowledgment,ifTCPlostpackets4and7outofan8-packetwindow,TCPwouldreceiveacknowledgmentofonlypackets1,2,and3.Packets

4through8wouldneedtobere-sent.Withselectiveacknowledgment,TCPreceivesacknowledgmentofpackets1,2,3,5,6,and8.Onlypackets4and7mustbe

re-sent.

TCPselectiveacknowledgmentisusedonlywhenmultiplepacketsaredroppedwithinoneTCPwindow.

Thereisnoperformanceimpactwhenthefeatureis

enabledbutnotused.Usetheiptcpselective-ackcommandinglobalconfigurationmodetoenableTCPselectiveacknowledgment.

RefertoRFC2018formoredetailsaboutTCPselectiveacknowledgment.

TCPTimeStamp

TheTCPtime-stampoptionprovidesimprovedTCPround-triptimemeasurements.Becausethetimestampsarealwayssentandechoedinbothdirectionsandthetime-stampvalueintheheaderisalwayschanging,TCPheadercompressionwillnotcompresstheoutgoingpacket.ToallowTCPheadercompressionoveraseriallink,theTCPtime-stampoptionisdisabled.UsetheiptcptimestampcommandtoenabletheTCPtime-stampoption.

TCPExplicitCongestionNotification

TheTCPExplicitCongestionNotification(ECN)featureallowsanintermediateroutertonotifyendhostsofimpendingnetworkcongestion.ItalsoprovidesenhancedsupportforTCPsessionsassociatedwithapplications,suchasTelnet,webbrowsing,andtransferofaudioandvideodatathataresensitivetodelayorpacketloss.Thebenefitofthisfeatureisthereductionofdelayandpacketlossindatatransmissions.

UsetheiptcpecncommandinglobalconfigurationmodetoenableTCPECN.

TCPKeepaliveTimer

TheTCPKeepaliveTimerfeatureprovidesamechanismtoidentifydeadconnections.WhenaTCPconnectiononaroutingdeviceisidlefortoolong,thedevicesendsaTCPkeepalivepackettothepeerwithonlytheAcknowledgment(ACK)flagturnedon.Ifaresponsepacket(aTCPACKpacket)isnotreceivedafterthedevicesendsaspecificnumberofprobes,theconnectionisconsidereddeadandthedeviceinitiatingtheprobesfreesresourcesusedbytheTCPconnection.Reference:http://

/c/en/us/td/docs/ios-xml/ios/ipapp/configuration/xe-3s/asr1000/iap-xe-3s-asr1000-book/iap-

tcp.html#GUID-22A82C5F-631F-4390-9838-F2E48FFEEA01

QUESTION11

AnetworkadministratorusesIPSLAtomeasureUDPperformanceandnoticesthatpacketsononerouterhaveahigherone-waydelaycomparedtotheoppositedirection.WhichUDPcharacteristicdoesthisscenariodescribe?

latency

starvation

connectionlesscommunication

nonsequencingunorderedpackets

jitter

CorrectAnswer:ASection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:

CiscoIOSIPSLAsprovidesaproactivenotificationfeaturewithanSNMPtrap.Eachmeasurementoperationcanmonitoragainstapre-setperformancethreshold.

CiscoIOSIPSLAsgeneratesanSNMPtraptoalertmanagementapplicationsifthisthresholdiscrossed.SeveralSNMPtrapsareavailable:roundtriptime,

averagejitter,one-waylatency,jitter,packetloss,MOS,andconnectivitytests.HereisapartialsampleoutputfromtheIPSLAstatisticsthatcanbeseen:router#showipslastatistics1

RoundTripTime(RTT)forIndex55LatestRTT:1ms

Latestoperationstarttime:*23:43:31.845UTCThuFeb32005Latestoperationreturncode:OKRTTValues:

NumberOfRTT:10RTTMin/Avg/Max:1/1/1millisecondsLatencyone-waytime:NumberofLatencyone-waySamples:0

SourcetoDestinationLatencyonewayMin/Avg/Max:0/0/0millisecondsDestinationtoSourceLatencyonewayMin/Avg/Max:0/0/0millisecondsReference:

/en/US/technologies/tk648/tk362/tk920/technologies_white_paper09186a0

0802d5efe.html

QUESTION12

UnderwhichconditiondoesUDPdominanceoccur?

whenTCPtrafficisinthesameclassasUDP

whenUDPflowsareassignedalowerpriorityqueue

whenWREDisenabled

whenACLsareinplacetoblockTCPtraffic

CorrectAnswer:ASection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:MixingTCPwithUDPItisageneralbestpracticetonotmixTCP-basedtrafficwithUDP-basedtraffic(especiallyStreaming-Video)withinasingleservice-providerclassbecauseofthebehaviorsoftheseprotocolsduringperiodsofcongestion.Specifically,TCPtransmittersthrottlebackflowswhendropsaredetected.AlthoughsomeUDPapplicationshaveapplication-levelwindowing,flowcontrol,andretransmissioncapabilities,mostUDPtransmittersarecompletelyoblivioustodropsand,thus,neverlowertransmissionratesbecauseofdropping.WhenTCPflowsarecombinedwithUDPflowswithinasingleservice-providerclassandtheclassexperiencescongestion,TCPflowscontinuallylowertheirtransmissionrates,potentiallygivinguptheirbandwidthtoUDPflowsthatareoblivioustodrops.ThiseffectiscalledTCPstarvation/UDPdominance.TCPstarvation/UDPdominancelikelyoccursif(TCP-

based)Mission-CriticalDataisassignedtothesameservice-providerclassas(UDP-based)Streaming-Videoandtheclassexperiencessustainedcongestion.EvenifWREDisenabledontheservice-providerclass,thesamebehaviorwouldbeobservedbecauseWRED(forthemostpart)managescongestiononlyonTCP-basedflows.Reference:

/c/en/us/td/docs/solutions/Enterprise/

WAN_and_MAN/QoS_SRND/QoS-SRND-Book/VPNQoS.html

QUESTION13

PriortoenablingPPPoEinavirtualprivatedialupnetworkgroup,whichtaskmustbecompleted?

DisableCDPontheinterface.

Executethevpdnenablecommand.

Executethenoswitchportcommand.

EnableQoSFIFOforPPPoEsupport.

CorrectAnswer:BSection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:

EnablingPPPoEinaVPDNGroup

PerformthistasktoenablePPPoEinavirtualprivatedial-upnetwork(VPDN)group.Restrictions

ThistaskappliesonlytoreleasespriortoCiscoIOSRelease12.2(13)T.SUMMARYSTEPS

1.

enable

2.

configureterminal

3.

vpdnenable

4.

vpdn-groupname

5.

request-dialin

6.

protocolpppoeDETAILEDSTEPSCommandorActionPurposeStep1enableEnablesprivilegedEXECmode.Example:·EnteryourpasswordifRouter>enableprompted.Step2configureterminalEntersglobalconfigurationmode.Example:Router#configureterminalStep3vpdnenableEnablesvirtualprivatedialupExample:networking.Router(config)#vpdnenableStep4vpdn-groupnameAssociatesaVPDNgroupwithaExample:customerorVPDNprofile.Router(config)#vpdn-groupgroup1Step5request-dialinCreatesarequest-dialinVPDNExample:subgroup.Router(config-vpdn)#request-dialinStep6protocolpppoeEnablestheVPDNsubgrouptoExample:establishPPPoERouter(config-vpdn-req-in)#protocolpppoe

Reference:

/en/US/docs/ios/12_2t/12_2t2/feature/guide/ftpppoec_support_TSD_Island

_of_Content_Chapter.html

QUESTION14

AnetworkengineerhasbeenaskedtoensurethatthePPPoEconnectionisestablishedandauthenticatedusinganencryptedpassword.Whichtechnology,incombinationwithPPPoE,canbeusedforauthenticationinthismanner?

PAP

dot1x

IPsec

CHAP

ESP

CorrectAnswer:DSection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:WithPPPoE,thetwoauthenticationoptionsarePAPandCHAP.WhenCHAPisenabledonaninterfaceandaremotedeviceattemptstoconnecttoit,theaccessserversendsaCHAPpackettotheremotedevice.TheCHAPpacketrequestsor"challenges"theremotedevicetorespond.ThechallengepacketconsistsofanID,arandomnumber,andthehostnameofthelocalrouter.Whentheremotedevicereceivesthechallengepacket,itconcatenatestheID,theremotedevice'spassword,andtherandomnumber,andthenencryptsallofitusingtheremotedevice'spassword.Theremotedevicesendstheresultsbacktotheaccessserver,alongwiththenameassociatedwiththepasswordusedintheencryptionprocess.Whentheaccessserverreceivestheresponse,itusesthenameitreceivedtoretrieveapasswordstoredinitsuserdatabase.Theretrievedpasswordshouldbethesamepasswordtheremotedeviceusedinitsencryptionprocess.Theaccessserverthenencryptstheconcatenatedinformationwiththenewlyretrievedpassword--iftheresultmatchestheresultsentintheresponsepacket,authenticationsucceeds.ThebenefitofusingCHAPauthenticationisthattheremotedevice'spasswordisnevertransmittedincleartext(encrypted).ThispreventsotherdevicesfromstealingitandgainingillegalaccesstotheISP'snetwork.Reference:

/c/en/us/td/docs/ios/12_2/security/configuration/

guide/fsecur_c/scfathen.html

QUESTION15

AcorporatepolicyrequiresPPPoEtobeenabledandtomaintainaconnectionwiththeISP,evenifnointerestingtrafficexists.Whichfeaturecanbeusedtoaccomplishthistask?

TCPAdjust

DialerPersistent

PPPoEGroups

half-bridging

PeerNeighborRoute

CorrectAnswer:BSection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:

Anewinterfaceconfigurationcommand,dialerpersistent,allowsadial-on-demandrouting(DDR)dialerprofileconnectiontobebroughtupwithoutbeingtriggered

byinterestingtraffic.Whenconfigured,thedialerpersistentcommandstartsatimerwhenthedialerinterfacestartsupandstartstheconnectionwhenthetimer

expires.Ifinterestingtrafficarrivesbeforethetimerexpires,theconnectionisstillbroughtupandsetaspersistent.Thecommandprovidesadefaulttimerinterval,

oryoucansetacustomtimerinterval.Toconfigureadialerinterfaceaspersistent,usethefollowingcommandsbeginninginglobalconfigurationmode:

CommandPurpose

Step1Router(config)#interfacedialerCreatesadialerinterfaceandnumberentersinterfaceconfiguration

mode.

Step2Router(config-if)#ipaddressSpecifiestheIPaddressandmaskaddressmaskofthedialerinterfaceasanodein

thedestinationnetworktobecalled.

Step3Router(config-if)#encapsulationSpecifiestheencapsulationtype.type

Step4Router(config-if)#dialerstringSpecifiestheremotedestinationtodial-stringclassclass-namecallandthemapclassthatdefinescharacteristicsforcallsto

thisdestination.

Step5Router(config-if)#dialerpoolSpecifiesthedialingpooltousenumberforcallstothisdestination.Step6Router(config-if)#dialer-groupAssignsthedialerinterfacetoagroup-numberdialergroup.

Step7Router(config-if)#dialer-listSpecifiesanaccesslistbylistdialer-groupprotocolprotocol-numberorbyprotocolandlistname{permit|deny|listnumberto

definetheinterestingaccess-list-number}packetsthatcantriggeracall.Step8Router(config-if)#dialer(Optional)Specifiestheremote-nameuser-name

authenticationnameoftheremoterouteronthedestinationsubnetworkforadialerinterface.

Step9Router(config-if)#dialerForcesadialerinterfacetobepersistent[delay[initial]connectedatalltimes,eveninseconds|max-attemptstheabsenceof

interestingtraffic.number]

Reference:

/c/en/us/td/docs/ios/dial/configuration/guide/12_4t/dia_12_4t_book/dia_dia

ler_persist.html

QUESTION16

WhichPPPauthenticationmethodsendsauthenticationinformationincleartext?

MSCHAP

CDPCP

CHAP

PAP

CorrectAnswer:DSection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:PAPauthenticationinvolvesatwo-wayhandshakewheretheusernameandpasswordaresentacrossthelinkincleartext;hence,PAPauthenticationdoesnotprovideanyprotectionagainstplaybackandlinesniffing.CHAPauthentication,ontheotherhand,periodicallyverifiestheidentityoftheremotenodeusingathree-wayhandshake.AfterthePPPlinkisestablished,thehostsendsa"challenge"messagetotheremotenode.Theremotenoderespondswithavaluecalculatedusingaone-wayhashfunction.Thehostcheckstheresponseagainstitsowncalculationoftheexpectedhashvalue.Ifthevaluesmatch,theauthenticationisacknowledged;otherwise,theconnectionisterminated.Reference:

/c/en/us/support/docs/wan/point-to-point-protocol-ppp/10241-

ppp-callin-hostname.html

QUESTION17

Whichprotocolusesdynamicaddressmappingtorequestthenext-hopprotocoladdressforaspecificconnection?

FrameRelayinverseARP

staticDLCImapping

FrameRelaybroadcastqueue

dynamicDLCImapping

CorrectAnswer:ASection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:

DynamicaddressmappingusesFrameRelayInverseARPtorequestthenext-hopprotocoladdressforaspecificconnection,givenitsknownDLCI.Responsesto

InverseARPrequestsareenteredinanaddress-to-DLCImappingtableontherouteroraccessserver;thetableisthenusedtosupplythenext-hopprotocol

addressortheDLCIforoutgoingtraffic.Reference:

/c/en/us/td/docs/ios/12_2/wan/configuration/guide/fwan_c/wcffrely.html

QUESTION18

WhatisthedefaultOSPFhellointervalonaFrameRelaypoint-to-pointnetwork?

10

20

30

40

CorrectAnswer:ASection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:BeforeyoutroubleshootanyOSPFneighbor-relatedissuesonanNBMAnetwork,itisimportanttorememberthatanNBMAnetworkcanbeconfiguredinthesemodesofoperationwiththeipospfnetworkcommand:Point-to-PointPoint-to-MultipointBroadcastNBMATheHelloandDeadIntervalsofeachmodearedescribedinthistable:HelloIntervalDeadIntervalNetworkType(secs)(secs)Point-to-Point1040Point-to-Multipoint30120Broadcast1040Non-Broadcast30120

Reference:

/c/en/us/support/docs/ip/open-shortest-path-first-ospf/13693-

22.html

QUESTION19

PPPoEiscomposedofwhichtwophases?

ActiveAuthenticationPhaseandPPPSessionPhase

PassiveDiscoveryPhaseandPPPSessionPhase

ActiveAuthorizationPhaseandPPPSessionPhase

ActiveDiscoveryPhaseandPPPSessionPhase

CorrectAnswer:DSection:(none)Explanation

Explanation/Reference:

Explanation/Reference:

Explanation:

PPPoEiscomposedoftwomainphases:

ActiveDiscoveryPhase--Inthisphase,thePPPoEclientlocatesaPPPoEserver,calledanaccessconcentrator.Duringthisphase,aSessionIDisassignedand

thePPPoElayerisestablished.

PPPSessionPhase--Inthisphase,PPPoptionsarenegotiatedandauthenticationisperformed.Oncethelinksetupiscompleted,PPPoEfunctionsasaLayer2

encapsulationmethod,allowingdatatobetransferredoverthePPPlinkwithinPPPoEheaders.

Reference:

/c/en/us/td/docs/security/asa/

asa92/configuration/vpn/asa-vpn-cli/vpn-pppoe.html

QUESTION20

WhichstatementistrueaboutthePPPSessionPhaseofPPPoE?

PPPoptionsarenegotiatedandauthenticationisnotperformed.Oncethelinksetupiscompleted,PPPoEfunctionsasaLayer3encapsulationmethodthatallowsdatatobetransferredoverthePPP

linkwithinPPPoEheaders.

PPPoptionsarenotnegotiatedandauthenticationisperformed.Oncethelinksetupiscompleted,P