51CTO下载Cisco+Certified+Network+Associate.docx

51CTO下载Cisco+Certified+Network+Associate.docx

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51CTO下载Cisco+Certified+Network+Associate

CiscoCertifiedNetworkAssociate

由于权限问题，上传不了大附件，需要完整的请去

Number:

640-802

PassingScore:

800

TimeLimit:

120min

QUESTION1

BothswitchesandhubsarebeingutilizedwithintheTestKingnetwork.Whichofthefollowingistrueregardingtheuseofswitchesandhubsfornetworkconnectivityinthisnetwork?

A.

Switchestakelesstimetoprocessframesthanhubstake

B.

Hubscanfilterframes

C.

Switchesdonotforwardbroadcasts

D.

Switchesincreasethenumberofcollisiondomainsinthenetwork

E.

Usinghubscanincreasetheamountofbandwidthavailabletohosts

F.

Noneoftheotheralternativesapply

Answer:

D

Section:

（none）

Explanation/Reference:

Explanation:

Thebiggestbenefitofusingswitchesinsteadofhubsinyourinternetworkisthateachswitchportisactuallyitsowncollisiondomain.（Conversely,ahubcreatesonelargecollisiondomain.）Butevenarmedwithaswitch,youstillcan'tbreakupbroadcastdomains.Neitherswitchesnorbridgeswilldothat.They'lltypicallysimplyforwardallbroadcastsinstead.Switchcreatesthecollisiondomainperport,sowecansayswitchincreasethenumberofcollisiondomains.

QUESTION2

Whichoneofthefollowingcharacteristicsistrueregardingtheuseofhubsandswitches?

A.

HubscanhavetheirportsbeconfiguredwithVLANs

B.

Usinghubsiscostlywithregardtobandwidthavailability.

C.

Switchescannotforwardbroadcasts.

LeadingthewayinITtestingandcertificationtools,

D.

Switchesaremoreefficientthanhubsinprocessingframes.

E.

Switchesincreasethenumberofcollisiondomainsinthenetwork.

Answer:

E

Section:

（none）

Explanation/Reference:

Explanation:

Switchesincreasesthenumberofcollisionsdomainsinthenetwork.SwitchesthatareconfiguredwithVLANswillreducethesizeofthecollisiondomainsbyincreasingthenumberofcollisiondomainsinanetwork,butmakingthemsmallerthanthatofonebig,flatnetwork.

IncorrectAnswers:

A.SwitchesarecapableofVLANconfigurations,buthubsarenot.B.Hubsaregenerallytheleastcostlymethodpossibletoconnectmultipledevicestogetherinanetwork.

C.Switchesforwardbroadcastsandmulticasts,bydefault,toallportswithinthesameVLAN.Onlyroutersblockallbroadcasttrafficbydefault.D.Switchesandhubscanbeequallyefficientinprocessingframes,intheory.Inpractice,switchesaregenerallymoreefficientastheyusuallyhavemoreCPUandmemoryallocatedtothem,andaregenerallymuchmoreexpensivethanasimplehub.

QUESTION3

Whencomparingandcontrastingthesimilaritiesanddifferencesbetweenbridgesandswitches,whichofthefollowingarevalidstatements?

Chooseallthevalidanswerchoices）

A.

Bridgesarefasterthanswitchesbecausetheyhavefewerports.

B.

Aswitchisamultiportbridge,

C.

BridgesandswitcheslearnMACaddressesbyexaminingthesourceMACaddressofeachframereceived.

D.

Abridgewillforwardabroadcastbutaswitchwillnot.

E.

Bridgesandswitchesincreasethesizeofacollisiondomain.

F.

Noneoftheotheralternativesapplystatementsaretrue.

Answer:

BC

Section:

（none）

Explanation/Reference:

Explanation:

BothbridgesandswitchesbuildthebridgetablebylisteningtoincomingframesandexaminingthesourceMACaddressintheframe.

Switchesaremultiportbridgesthatallowyoutocreatemultiplebroadcastdomains.Eachbroadcastdomainislikeadistinctvirtualbridgewithinaswitch.

IncorrectAnswers:

LeadingthewayinITtestingandcertificationtools,A.Switchesaregenerallyfasterthanbridges.Bridgesalsodonotnecessarilyhavefewerportsthanswitches.

D.Bothbridgesandswitcheswillforwardbroadcastandmulticasttraffic,assumingthatthetrafficremainsinthesameVLAN.

E.TheuseofVLANsinaswitchcandecreasethesizeofthecollisiondomain,bycreatingadditional,smallercollisiondomains.

QUESTION4

Whichofthefollowingcorrectlydescribethevariousfunctionsandvirtuesofarouter?

（Selectallvalidanswerchoices）

A.

Packetswitching

B.

CollisionpreventiononaLANsegment.

C.

Packetfiltering

D.

Broadcastdomainenlargement

E.

Broadcastforwarding

F.

Internetworkcommunication

G.

Noneoftheotheralternativesapply

Answer:

ACF

Section:

（none）

Explanation/Reference:

Explanation:

Themainfunctionofarouteristoconnectdifferent,separatednetworkstogether.Indoingso,switchingpacketsfromonenetworktoanotherisaprimaryfunction,alongwithprovidingforcommunicationbetweennetworks.Asanadditionalfeature,routersarecapableofprovidingfilteringonanetworkaddressandapplicationportlevel,sochoiceCisalsocorrect.

IncorrectAnswers:

B.Routerscanindeedbeusedtosegmentanetworkseparateacollisiondomain,sinceroutersdonotforwardLANbroadcastsandmulticaststootherinterfaces.However,routersalonecannotpreventallcollisionsfromoccurringonanygivenLANsegment.D.RoutersactuallysegmentLANsintosmallerbroadcastdomains.E.Routersdonotforwardbroadcastandmulticasttrafficouttheadditionalinterfacesbydefault.UnlessbridgingorIPhelpersareconfiguredontherouter,LANbroadcastsareblockedattherouterlevel.

QUESTION5

LeadingthewayinITtestingandcertificationtools,TheLANneedsareexpandingattheTestkingcorporateoffice,whichisquicklygrowing.YouareinstructedtoenlargetheareacoveredbyasingleLANsegmentontheTestKingnetwork.

Whichofthefollowingarelayer1devicesthatyoucanuse?

（Chooseallthatapply.）

A.

Aswitch

B.

Arouter

C.

Anetworkadaptercard

D.

Ahub

E.

Arepeater

Answer:

DE

Section:

（none）

Explanation/Reference:

Explanation:

Ahubsimplyrepeatstheelectricalsignalandmakesnoattempttointerprettheelectricalsignal（layer1）asaLANframe（Layer2）.So,ahubactuallyperformsOSIlayer1functions,repeatinganelectricalsignal,whereasaswitchperformsOSIlayer2functions,actuallyinterpretingEthernetheaderinformation,particularlyaddresses,tomakeforwardingdecisions.HubscanbeusedtoincreasethenumberofstationsthatcanbesupportedonaLAN.

Becausetherepeaterdoesnotinterpretwhatthebitsmean,butdoesexamineandgenerateelectricalsignals,arepeaterisconsideredtooperateatLayer1.RepeaterscanbeusedtophysicallyextendtheLANtogreaterdistances.

QUESTION6

Ciscoistheleaderintheroutermarketspace.Whatbasicfunctionsdotheirroutersperforminanetwork?

（Choosetwo）

A.

Themicro-segmentationofbroadcastdomains

B.

Pathselection

C.

Packetswitching

D.

BridgingbetweenLANsegments

E.

Accesslayersecurity

F.

VLANmembershipassignment

G.

Applicationoptimization

Answer:

BC

Section:

（none）

Explanation/Reference:

Explanation:

LeadingthewayinITtestingandcertificationtools,Theprimaryfunctionsofarouterare:

PacketSwitchingandPathSelection.Itistheroutersjobtodeterminethebestmethodfordeliveringthedata,andswitchingthatdataasquicklyaspossible.

QUESTION7

BothbridgesareswitchesarebeingusedthroughouttheTestKingLAN.Whichofthefollowingstatementsaretrueregardingbridgesandswitchesinthisnetwork?

（Choose3）

A.

Switchesareprimarilysoftwarebasedwhilebridgesarehardwarebased.

B.

Switchesusuallyhaveahighernumberofportsthanmostbridges.

C.

Bridgesarefrequentlyfasterthanswitches.

D.

Bridgesdefinebroadcastdomainswhileswitchesdefinecollisiondomains.

E.

BothbridgesandswitchesforwardLayer2broadcasts.

F.

BothbridgesandswitchesmakeforwardingdecisionsbasedonLayer2addresses.

Answer:

BEF

Section:

（none）

Explanation/Reference:

Explanation:

BothbridgesandswitchesoperateatthesecondlayeroftheOSImodel,processingandforwardingframesfromthedata-linklayer.

Bridgesaresoftwarebasedandswitchesarehardwarebased.

Switcheshavemoreportsthanbridges.

BothbridgesandswitchesforwardframesbasedonMACaddresses.

QUESTION8

Asanetworkadministrator,youwillneedtodecideontheappropriatenetworkdevicestouse.WhichofthefollowingcorrectlydescribestherolesofdevicesinaWAN?

（Choosethree）

A.

ACSU/DSUterminatesadigitallocalloop.

B.

ArouteriscommonlyconsideredaDCEdevice.

C.

Amodemterminatesananaloglocalloop.

D.

ArouteriscommonlyconsideredaDTEdevice.

E.

Amodemterminatesadigitallocalloop.

F.

ACSU/DSUterminatesananaloglocalloop.

G.

AmodemisusedtoterminateaT1

LeadingthewayinITtestingandcertificationtools,

Answer:

ACD

Section:

（none）

Explanation/Reference:

Explanation:

Layer2switchingisconsideredhardware-basedbridgingbecauseitusesspecializedhardwarecalledanapplication-specificintegratedcircuit（ASIC）.ASICscanrunuptogigabitspeedswithverylowlatencyrates.

ArouteriscommonlyconsideredtobeaDTEdevice,whileaCSU/DSUisconsideredtheDCEdevice.

Switchesusuallyhavehigherportnumberthenbridge.Generallybridgeshavetwoports.

BothoperateonDatalinklayer.

QUESTION9

TheTestKingnetworkadministratorneedstodeterminewhatLANdevicestoinstallontheTestKingnetwork.WhataretwoadvantagesofusingLayer2Ethernetswitchesoverhubs?

（Choosetwo）

A.

Allowingsimultaneousframetransmissions

B.

Increasingthesizeofbroadcastdomains

C.

IncreasingthemaximumlengthofUTPcablingbetweendevices

D.

FilteringframesbasedonMACaddresses

E.

Decreasingthenumberofcollisiondomains

Answer:

AD

Section:

（none）

Explanation/Reference:

Explanation:

A:

Ahalfduplexconnectionisw