2023年計(jì)算機(jī)網(wǎng)絡(luò)英文題庫附答案

Ｃｈapter3TｒａｎsｐortLａyer1．Ａｔｒanｓpｏｒt-laｙｅrprotｏcoｌpｒｏｖiｄｅｓforｍｕｎicatｉonbetween__＿_(dá).AＡpplicatｉonprｏcessｅsＢHostｓCRoutersDEndsysteｍｓ２.Traｎsport-layeｒproｔocolsrunin__＿_(dá)．ＡSｅｒvｅrsBClienｔsCRoutersＤEｎdsｙstｅms3．Ｉｎｔｒａｎspｏrtlayer,ｔhesｅndsｉdebreaｋsａpplicaｔiｏnmesｓａgesinto_＿_(dá)_,pａsｓeｓtonｅtwｏｒkｌaｙeｒ．AＦraｍesBＳegmenｔsCＤatａ－ｇｒａmsDbitstｒｅａmｓ4.Seｒviceｓprovideｄbytranspｏｒtｌａｙerｉnclｕde_＿＿_(dá)．ＡHTTPandFＴＰBTCＰanｄIPＣTCPandUDPDSMＴＰ5.WhｉchｏｆｔｈefｏlloｗｉnｇsｅrｖｉcesisnotｐrovidedbyTＣP?AＤｅlayｇuａｒａｎteｅｓandbaｎｄwidtｈguaｒanteｅｓBRelｉabledａｔaｔｒａnsｆｅｒsａndflｏｗcｏｎtrolsCCoｎgｅstioncontrolsDIn-ordeｒdatatraｎｓfers６.Theｓetwomｉｎimalｔrａnｓｐｏｒt-layerserｖices－---_＿_(dá)＿ａnｄ_＿_(dá)_－---areｔｈeonlytｗoｓervicｅｓthａt(yī)UDPｐrｏvidｅs！Apｒocess-tｏ-ｐｒoceｓｓdatadeｌiｖery,eｒrorcheｃkiｎgBcongesｔiｏnconｔｒol，ｒeliabledatatｒａnｓferＣfｌowｃｏntrol，congestionｃoｎtrolDＩn-orderｄａt(yī)ａt(yī)rａnsfeｒ，errorｃhecｋing7.Ｐorｔnuｍber’ｓscopｅiｓ__＿_(dá)tｏ____．A0,１0２３Ｂ0,６553５Ｃ０,１27D0,２5５8.Tｈeporｔｎumｂｅrsrangｉngfrｏm___＿ｔo___＿arecａlｌedwｅｌl-ｋnownpoｒtｎumbeｒandaｒereｓtｒicteｄ．Ａ０,10２3Ｂ0,6５53５C0,127Ｄ0，２55９.ＵDPsoｃｋｅｔｉdenｔiｆieｄbytwｏcomponeｎts,ｔheyare____.AsourｃeIＰaddrｅsseｓanｄsoｕｒcｅｐortnumｂersBｓｏuｒceＩPａｄｄresｓesanｄdestinａｔionＩPａddresｓesＣdesｔinatiｏnIPaddrｅssandｄeｓtiｎａｔiｏnpｏrtnumｂersDdestinatiｏnpｏｒｔnｕmbeｒｓａｎdsoｕrcｅpｏrtnumbers10.TCPsockｅtidｅnｔiｆｉedbｙa(an）＿_(dá)＿_(dá)．A1-tuｐleB2－ｔuｐｌeＣ3-ｔupleD4-tｕple11．WhichｏftｈefｏllowiｎgapplicationsnｏｒmalｌyｕsｅsＵDPsｅrviceｓ?AＳMTPBSｔrｅamingｍｕｌtimediaCＦTPDHTＴP１２.

Relｉａble

daｔa

transfｅr

ｐroｔｏcol

over

a

ｐerfｅctly

relｉａblｅ

cｈａnnel

iｓ____.

A

rdt1.0

B

rdｔ2.０

Ｃ

ｒdt3.0

D

rｄt2．1

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data

tｒansｆeｒ

protｏcol

ｏvｅr

ａ

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ｗiｔh

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errors

aｎd

paｃket

losｓes

is

＿_(dá)__．

A

ｒdt１.0

B

ｒｄt2.0

C

ｒdt3.0

Ｄ

rdt2.1

14.

Ｗhｉcｈ

of

the

foｌlｏwiｎg

ａbout

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dａt(yī)a

tranｓfｅr

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bｉt

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assｕmｉng

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RDT2.2：

only

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RDT２.2:

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15.

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pipelinｉng

protoｃolｓ?

A

TCP

B

rdt3．0

C

ＧO－ＢACK-N

D

selectivｅ

ｒｅpeat

1６.

Which

of

tｈe

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about

GBN

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A

Onｌｙ

ｕｓｉｎｇ

ACK-s

B

Uｓｉng

cumulatiｖe

ＡCK－s

C

Receivｅr

ｄiｓcaｒｄs

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out-ｏf－order

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D

It

is

nｏt

pipelｉned

prｏtocｏｌ

17.

Whiｃh

of

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SR

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A

ｒeceｉver

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aｌl

coｒrectly

received

ｐacｋｅtｓ

B

senｄeｒ

only

rｅｓends

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which

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C

Ｉt

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sequｅnce

numbeｒ

of

sｅnt

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un-ＡＣK－eｄ

packets

Ｄ

It

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To

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Inｔｅrnet

emploｙs

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____

pｒoｔocｏl.

A

FTP

B

TCＰ

C

ＩＧMP

D

UDP

36.Ｉfanaｐｐliｃationdeveloｐerchoｏｓｅｓ_＿_(dá)＿protocol，tｈentｈｅapplｉｃaｔionprｏｃeｓsiｓalmｏstdｉrectlytaｌｋｉnｇwiｔhIP.AHＴTPBRIPCCSMＡ/CDDUDP37._＿_(dá)＿maintainsconnectiｏn－ｓtatｅintheeｎdsyｓtems.Thisconneｃtionsｔａt(yī)eiｎcludｅｓrｅceiveａndsｅndｂuffers,congeｓtｉon-controｌｐaramｅteｒs，aｎdｓeｑｕeｎcｅaｎｄackｎowleｄgmｅntnｕmｂeｒpaｒametｅrs.AＵDP BTCP? CDＮS DHTTP38.Ｔhehostｔhａt(yī)initｉaｔesthesessioninｔｈeInternｅtiｓlabeledaｓ＿_(dá)__.Aserver?Bｕｓerａgeｎｔ?Ｃcｌｉｅnｔ??Drouter3９.WｉthTCＰthｅｒeisno_＿_(dá)_＿bｅtｗｅeｎsｅｎdinganｄreceiviｎgtranｓporｔ-layｅｒentiｔies．Aflowcｏｎtｒol BhandshakingＣ.coｎgesｔｉｏnｃoｎtｒoｌ ＤVＣsetuｐ40.ＴｈｅInterｎeｔ’ｓ_＿_(dá)_ｓervicｅhｅlpspreventtheIｎｔｅrnetfｒomenterｉnｇastａt(yī)ｅofgrｉdloｃｋ.Adａt(yī)agｒam? ? BｃongesｔｉoncontｒoｌCsｌidinｇｗiｎdoｗ? Dｔｉmeoｕtｅvent41.Conｎｅcｔioｎseｔｕpattｈetranｓpｏrtlaｙerinvolves_＿_(dá)＿.Ａｓerver ? ?BonlytｈｅtwoendsystｅmsCcｌｉeｎt ? Ｄｒｏｕｔer42.A____lａyｅｒpｒotoｃolｐrovidesfoｒlogiｃａlcommｕnicaｔiｏnｂｅtwｅenapｐlicａt(yī)ｉｏns.AｔｒansｐoｒtBaｐplicatiｏnCｎetｗｏrkingDＭAC43.Ｉnｓtａt(yī)icconｇｅstｉｏｎwindow,ｉfitsａｔｉsｆieｓW*S/R>RＴＴ+Ｓ/Ｒ，theＬａt(yī)enｃyｉs____.AW*S/R–(RTＴ+S/R）B２RTT+O/ＲＣ2RTＴ+O/R＋(k-1)[W*Ｓ/Ｒ-(RＴT+Ｓ/Ｒ)］D２RＴT+Ｓ/Ｒ４4.Therecｅiｖｅｓideｏftraｎspｏrtlayerreａsｓｅｍblessegmentsintｏｍｅssages,passesｔo____laｙer．ＡApplicatｉonBNｅｔwｏrｋingCPhｙｓicａlDMAＣ45.Ｉnthefollowingｆoｕroptioｎｓ,ｗhicｈoｎeiｓcorrect?ＡThｅｖariａt(yī)ionｓiｎtheSampleRＴTaresｍoothedｏutiｎthecomputａt(yī)iｏnofthｅEstimａt(yī)edRTTBＴhetimeoutshｏｕldbｅlesｓtｈantheconnectiｏn’sＲTTＣSuｐposｅthatｔhelasｔSamplｅRTTｉnａTCPconｎecｔionisequａlto1sec．TｈenｔｈeｃurrenｔvalueｏfTimeoｕｔIntervalwｉｌlnecｅssarｉlybｅ≥1secDSuppｏsethａｔthelastSaｍｐleRTTinaＴCPｃonｎectionｉｓｅｑualto１sｅc.ThentｈecuｒreｎtvalueofTimeoutＩnterｖalｗilｌnecesｓarilyｂe≤１seｃ４６.TheportｎumbeｒusedｂyＨTＴＰiｓ___＿.A80Ｂ２5C1１０Ｄ５３47.TｈepoｒｔnｕmberusｅdｂySMTPｉs_＿_(dá)_.A80B25C1１０D534８.Thepoｒtnumbeｒusedbypop3iｓ＿_(dá)__.A８0B2５C110Ｄ53４9.TｈepoｒｔnｕmberｕseｄbyDＮSis__＿_(dá).A80B25Ｃ110D5３50.TheｐoｒtnumberusｅdbyＦTPｉs__＿_(dá)．Ａ２0and21B20C21D5351.AUＤＰsｏcｋetideｎｔiｆiｅｄbｙa___＿ｔuｐｌe(s).A2B４Ｃ1D3５２.ATCPsｏｃkeｔidentiｆｉedbya_＿_(dá)_tｕｐlｅ(s)．A2B4Ｃ1D3５3.ＡTＣPsocketdｏｅsｎotincｌuｄe_＿_(dá)_．ＡSourceMＡCaddｒessBSｏurｃeportnumberCDｅstinａｔionＩPaddｒessDDｅｓｔinａt(yī)ｉonｐoｒｔｎumber5４.WhichoｆfolｌowiｎｇａｂoutUDPisnｏtcorｒｅct.ＡItisareｌiabledatａt(yī)ｒａnsferpｒotocｏlＢIｔｉsｃoｎｎectiｏnｌessCnｏhaｎdｓhakingｂetｗeｅｎUDPsｅnder，receｉｖerDｉtｉsａbｅstefｆortserviceprotocol55．DNSｕsｅs_＿_(dá)_sｅrvice.AＴCＰBUＤＰＣBotｈTCPaｎｄUＤＰDNｏneofabove56.WhｉchoffoｌｌowingaｂoｕtUDＰiscoｒreｃt？AFinerａｐplｉcａt(yī)ion－lｅvelconｔrolovｅrwhａt(yī)dataissent，andwｈenBNocｏnｎｅctionｅstablishｍent(whichcanadddｅlaｙ)，sonｏdelayfｏｒeｓtaｂlishaconneｃtionＣNoconｎectiｏnstate（sｏ,UDPcaｎtｙpｉｃａllyｓｕppｏｒtmaｎyａcｔivｅcｌienｔs)DLａｒgepacketheaｄeｒoveｒｈｅad(１6-B）57．Ｓtｒｅａmiｎgmｅdiausｅsa____sｅrvicｅnormallｙ．ＡTCPBUDPCBothTCＰandUDPＤNonｅoｆａboｖe58．TheUDPheａderhaｓonｌy___＿ｆiｅｌｄs.A2Ｂ4Ｃ1Ｄ3５9.WhｉchｏfｔhefｏlｌowingｄoeｓnotｉncluｄｅdｉnUDPheａｄer．ASourcｅpｏｒtnumｂerBＤｅsｔｉnationporｔnumberＣChｅcksumDＳeｑueｎｃenuｍber６０.Wｈｉchofｔhｅfolｌowinｇｉsnoｔaｐiｐeliningprotocoｌ．ARdt1．0BGｏ-Bａｃk-NCＳｅlectｉｖerｅpeａt(yī)DTCP61.InthefｏllowingfouｒdeｓｃriptiｏnsaboutMＳＳａndMTU,ｗhichoneｉｓｎotcorrect？AＴheMＳSisthemａximｕmamountｏfapplｉcａt(yī)ion-ｌayerdａt(yī)aiｎtｈeseｇｍentBThｅMSSｉsthemaximｕmｓiｚｅoftheTCPsegmeｎｔｉnclｕｄinｇhｅadｅrsCTheMSSisｔｙpicａｌlysｅｔbｙMＴUDTｈeMTUｍeanｓtheｌａrｇestlink-layerfｒame62．Tｈeｊｏbｏfgathｅｒingdataｃｈｕnkｓ,encapsulatｉｎgｅachdatａcｈｕnkwｉthheaderinfｏrｍationtocrｅatesｅgmenｔｓandpａsｓingthesｅgmｅntstoｔｈeneｔwｏrkiscalｌｅd____．AｍulｔｉpｌｅｘiｎgBde-multｉpleｘiｎgCｆｏrｗaｒｄｉngDrouｔｉng63.Inｔhefoｌlｏｗiｎgfourdeｓcriptionsａboutthereｌａt(yī)ｉonsｈipbeｔｗeeｎthetranspｏrtlayerandｔhenｅtwｏrklａyeｒ，ｗhichoneｉsnｏｔcorrecｔ？AＴｈetranｓpｏrt-layerpｒotｏcｏlｐｒovideslｏｇicalcoｍｍunicationｂeｔweenｈostsBTｈeｔrａｎsport-laｙerprｏtocolｐrovidesloｇicalｃoｍmuniｃationbetweenpｒocｅssesCＴheｓeｒｖicｅsｔhatatransｐorｔ-lａｙerｐｒｏtoｃolcanｐroviｄeａreｏfteｎcoｎstｒaｉnｅdbythｅｓerviceｍodelｏｆtheneｔｗｏｒk-laｙｅｒｐｒotocolDＡcｏmputernetworkmaｙmakeavaｉlablemultipletransｐｏrtｐｒｏtｏｃoｌs６4.Suppｏsｅthefollｏwiｎgtｈrｅe8-bitbytes:010１0101，01１10000,01001１00.Whａt(yī)’ｓtｈe1scoｍplemenｔofthesumofｔｈese8-biｔbｙtｅs？Ａ０0010001B1１１０１10１C00０10010D1000100065.Ｔｈefollowiｎgfouｒｄｅｓcriptiｏnsabouｔmｕltiplｅｘingandde－muｌtiｐｌexing，whｉｃｈonｅｉｓcorrｅｃt?ＡAＵDPｓocｋetisiｄentｉfｉedｂyatｗo-tuplesｃonｓistｉngｏｆasouｒceportnｕmｂeranｄadestinaｔioｎportnｕmber．BIfｔwｏUDPsegｍenthaｖeｄｉffｅreｎtｓｏuｒceｐortｎumbeｒ，theｙmaybedｉrecteｄtothｅsａｍeｄestinaｔiｏnprocess．CIftwｏTCPｓegｍentswｉｔhｄiffeｒeｎtｓｏｕrｃeｐortnumber,tｈeｙmaybediｒｅｃtedｔothesamedestiｎationprocess.DIftwoTCPｓegmentswitｈｓａmedestinａt(yī)iｏnIPａddressaｎｄdestinatｉonportnｕｍｂｅr,theymusｔｂｅｔhesaｍｅTCＰｃｏnnｅction.66.UＤPanｄＴCＰbothhaｖethefieldｓeｘｃept＿_(dá)＿_(dá).AｓourceportｎｕmbｅrＢdesｔinatioｎporｔnumbｅｒCｃhｅｃksuｍDrｅceiｖewindoｗ67.IｆweｄeｆineNtobetheｗinｄowsｉｚe,baseｔｏｂｅｔheｓｅqｕencenumberoftheolｄｅstuｎａｃknｏwlｅdgeｄｐacket,ａnｄnext-seq-nuｍtoｂethｅsmallｅｓｔｕｎｕseｄseqｕｅncｅnｕmber，tｈｅntｈeｉntｅｒｖal［ｎｅxtｓｅqnｕm,base＋N-1]correspondstoｐａckeｔthａt(yī)___＿.Acａnｂeｓentimmeｄiａt(yī)ｅlｙＢhavｅalreadｙｂeｅｎtraｎsmiｔｔeｄaｎdaｃkｎowledgedCcannｏｔbeuｓedDhavebeｅnsｅntbutnotyｅtaｃｋnowlｅdｇed68.ＷhicｈofthｅfｏｌｌoｗｉngａｂouｔTＣPisｎotcorrecｔ?AIｔiｓacｏnnｅctiｏnｌessprotocoｌBPoiｎt-tｏ-poiｎtpｒotｏｃoｌCReliable,in-ｏｒderbytestｅamprｏtｏcｏｌＤＰipelinｅdｐrｏtocol69．ＷｈｉcｈoｆｔhefolｌｏwingａbｏutＴＣPiｓnotcｏrｒect?AＩtiｓａconnectionlesｓprｏtｏcoｌBfulldｕplexdatａt(yī)ransferprotocolＣｃｏnｎectiｏn－oriｅntｅdprｏｔocolＤｆloｗconｔｒollｅｄpｒｏｔocol７0.Tｈemaximumamouｎtofｄatathatcanｂｅgrabbｅdandplacediｎａsegmentiｓlｉｍiｔｅdbytｈe____．AMaximｕmsegmentsiｚｅ(MSS)BＭTUCSequeｎceｎumberＤCheｃksｕm7１．ThｅＭSSiｓtyｐicallysｅtbyfirsｔｄeｔｅrｍinｉngtheｌeｎgtｈofthｅｌaｒgｅstｌink-ｌayerｆraｍetｈaｔcanbesentbyｔheloｃａｌsｅndingｈost（thesｏ-callｅd_＿_(dá)_),andｔhｅnwｉllfｉｔintｏaｓiｎglelink-layerframe.AMaximuｍsegmeｎtｓiｚe(MＳS)BMTUCSequenceｎｕｍberＤChｅｃkｓuｍ７2.TheMＳSisｔheｍaxiｍuｍamoｕntof____lａyerdaｔaintｈesegｍent,notｔhｅmaｘｉmｕmｓizeoftｈeTCPsegｍentinｃludｉngheadｅrs.ＡＡｐpliｃationBTransportCNeｔworkingDLｉｎk73.Whｉｃｈoｆthefｏllｏwingfｉeldisｎｏｔuｓedｆorconnｅctiｏnsｅtuｐandteaｒdｏｗn？ASequeｎcenｕｍberBＴＳTＣSＹNDFIN74.＿_(dá)__isｔｈeｂｙｔestreａmnumberｏffirｓtｂyteintheseｇｍｅｎt．AＳequｅncenｕmbｅrBＡCＫnｕｍberCCheｃkｓumＤｐoｒtｎumber75._＿_(dá)_isthｅbｙtｅseqｕｅｎcenｕmbeｒｓofnextbyteexpectedfroｍotheｒsｉde.ASｅquencenuｍbeｒBＡCＫnuｍbｅrCChecksumDportnumｂeｒ７６.BｅｃaｕsｅＴCPoｎlｙackｎowledgesbｙtesｕｐtｏthefirstmｉssiｎgbytｅintheｓtｒeaｍ,ＴＣPissａiｄtｏｐrovide_＿_(dá)_acｋｎｏwleｄgements.ＡＣumulatｉvｅBSeleｃtｉveCSinｇleDNｅgative７7．Ｆaｓtretranｓmitmｅａnsｉｎthecａseｔhaｔ_＿_(dá)_dｕpliｃateACK-sarｅreceiｖｅd,theTCPsenｄerresendsegmentbeforetｉmerexpireｓ.A3B４C5Ｄ678.ＴCＰ＿_(dá)__meaｎssenderwon’ｔoverflｏwｒｅceiver’sｂuffｅrbytraｎsmｉttｉnｇtoomuch,tｏｏfast.AFloｗｃoｎtｒｏｌBCongestioncｏｎtroｌCReliａbledatatransfｅrＤConnecｔion-oｒiｅｎteｄservice79.TCＰprovidesfｌowcoｎtrolｂyｈaｖiｎgtheseｎｄeｒmａｉntaｉnavariaｂｌeｃallｅｄthe_＿_(dá)_．ARecｅivｅwinｄｏwBＣｏngｅstionwiｎdowCSlidiｎgｗinｄowDbuffｅr80.HoｗｄoesTCPsｅnｄerｐeｒceivecｏngesｔｉon?ＡTimｅoｕtB3dupｌicａt(yī)ｅACK－sCBotｈAandBＤNoｎｅofabｏvｅ8１.Traｎｓｐtoｃｏｌsrｕnin_＿_(dá)_.ＡServersBClｉentsCRoutersＤEｎdｓysｔemｓ82.WhiｃhoｆtheｆｏllowingservicｅsisnoｔｐroviｄeｄｂyTCP?ADelaｙguarａnteesandbandｗｉｄｔｈguaranteesBＲeliablｅdａt(yī)atransfersaｎdflowcontｒolsCCongesｔｉｏｎcontrolsDIｎ-oｒdｅrdaｔatｒaｎsferｓ8３.WｈichserｖｉcedoesUDPnotprovide?ＡmuｌtipleｘingＢｄe-mulｔｉpleｘinｇＣeｒror-deｔｅｃｔｉonＤｅｒｒor-corrｅctioｎ8４.TherearethreemaｊorｅvｅntsｒｅｌaｔeｄtoｄatatｒaｎsmｉsｓionandretranｓmisｓionｉntｈeTCPsｅnｄer,ｗhｉchoneiｓnotｉnit?Ａｄatareceiveｄｆrｏmａppｌｉcａt(yī)ionabｏveBde-ｍultipleｘingsｅgmｅｎｔＣtiｍerｔimeoutDACKrｅｃｅipt85．ＷhｉｃhoｆtｈeｆｏlｌowｉnｇapplicationsnormａlｌyusesUDＰsｅrvｉceｓ?AＳMTPBStrｅａmｉnｇmｕltｉｍeｄiaCＦＴPDHTTP８6．WhicｈofthefｏllowｉｎgaboｕtＴＣPｃonnectioｎｉsｎotcorrect?AItisabroａdcaｓｔconｎecｔiｏnＢItiｓapoinｔ-to-poｉnｔｃoｎneｃｔｉoｎCItisapipｅlineｄconｎｅctionＤＩtｉsafｕlｌdｕpｌexｃonnectiｏn８7.ＴheSＹNsegmｅnｔｉsｕsedfor＿_(dá)＿＿.ATCPconnectionsｅtｕｐB(yǎng)TCＰｆlowcoｎｔrolＣTＣPcｏngｅsｔiｏncｏntｒoｌDＣloｓingaTＣＰconneｃｔioｎ8８.Whiｃhserviｃehｅlpsｐｒｅveｎtthｅiｎtｅｒnetfrｏmenｔｅringａstatｅofgrｉdｌock？AreｌｉaｂledatatｒansferBfloｗcｏntrｏｌCｃoｎgesｔｉoncontrｏlDhandｓhakinｇｐroceduｒe89．TheInteｒnｅt’s_____isｒespｏnsiblｅｆormｏvingpａｃkeｔsfｒoｍｏnehｏｓttoanｏther.AaｐplｉｃatioｎlayerBtransｐorｔlayerＣｎetｗoｒklayeｒDｌiｎklayerＩnｔhｅfｏllｏwingaｐｐｌicａt(yī)ｉons,wｈichoｎｅisabａndwiｄｔh-sensitiveapplｉｃａt(yī)ion?ＡE-mａilBwebapplｉcationＣreal-tiｍeauｄiｏDfｉletrａｎｓfeｒ91.Ｉnthefoｌｌowｉｎgappｌｉcations,whｉcｈonｅuseｓUDＰ？ＡE-ｍaiｌBweｂapplｉcａt(yī)ionCfｉleｔransｆeｒＤDNS92.Iｎthｅfoｌｌowiｎgｆouｒｄescriptioｎｓ,ｗhiｃhoneiscorrect?AIfｏneｈｏｓt’stranｓpｏｒtlａｙeruｓesTCP,ｔｈenｉtsnｅtworｋｌａｙｅrmusｔｕsevirtuａｌ-circuｉｔnetｗｏrｋ．BDatａｇrａｍnｅtｗoｒｋpｒｏvｉdesｃonｎｅctｉoｎservｉcｅＣThetraｎｓport－layerｃoｎｎeｃｔｉonseｒviceisｉmplｅｍentedｉntheroｕterDThenetｗork-ｌayｅrcoｎnectioｎservicｅiｓimpｌementeｄiｎtheroｕtｅrａsweｌlａｓinthｅendｓysｔem.____ｉsasｐeeｄiｎg-ｍａｔchｉngｓervice－--maｔｃhｉnｇtｈeｒatewhichthesｅｎｄeriｓsendingagainsttheratｅaｔｗhｉchｔhｅreceｉｖingａpplicａt(yī)ｉoniｓreadinｇ.AcｏngｅstionconｔrｏlBfｌowconｔrolＣslidiｎg-wｉndｏwcｏntｒolDvarｉablecｏntroｌ９4．InthefollｏwｉnｇfｏｕrdescripｔｉonsａboｕtRcv-Wiｎdow,wｈｉｃhonｅｉsｃorreｃｔ?AThesizｅoftｈeTＣPRcvWindoｗｎeverchangesthroｕghｏuｔthｅｄuraｔiｏnofthｅcｏnnectionＢTheｓｉzｅｏftheＴＣPRcvWindoｗwillcｈangeｗithｔhｅsizｅｏｆthｅTＣPRcvBufｆerＣＴhesizｅoｆthｅTCPRcvＷindoｗmuｓtｂelesstｈａnorequaltothｅｓｉｚeoftheTCPRcvBuffeｒDＳupｐoseｈosｔAｓendsafｉlｅtohｏｓtBoverａTＣPｃonnecｔiｏn,thenumberofuｎacknowlｅｄgedｂｙtestｈａｔAｓｅndscａnnｏtexceeｄtｈesizeｏftheｓizｅoftheＲcvWiｎdow．９５.Thereare6fｌagfｉeｌdｓ.Whiｃhoｎeistｏindicａt(yī)ｅtｈａｔｔｈerecｅivｅrshoｕlｄpａsｓthedataｔotheupｐeｒlａyerimｍediaｔely?AＰＳHＢURGCACＫDRST９6.SupposｅthｅＴCＰrｅｃeｉverreｃeｉｖｅｓtheｓegmｅｎtthａt(yī)paｒtiａllyorcompｌｅteｌｙfiｌｌsiｎgapinrｅcｅiｖeddａt(yī)a，iｔwill____.AｉmｍediatelｙｓendAＣKBｉｍmediatelyseｎｄdupｌicateAＣKＣwaitsomｅｔimeforarrivａlofanoｔhｅrin-oｒderｓegmenｔＤsendsiｎglecumulａt(yī)ivｅ９7.＿＿_(dá)_＿iｍposeｓcｏｎstrainoｎtheｒａｔeatｗｈichaTCPｓendercanｓenｄｔraｆficｉnｔoｔhｅnetwｏｒk.AsｌidｉｎgｗiｎdowBconｇｅstioｎｗiｎｄowＣreceivewiｎdoｗDvarｉａbｌeｗindｏw9８.Fｌowcontｒolａndcongestｉoncｏntｒolaresａmｅａｔthattｈｅｙalｌliｍitthｅratｅｏfthesendeｒ，ｂutdｉｆferｉnthat＿_(dá)＿_(dá).AｆlｏwｃonｔｒollｉmｉtsitsratebｙthesizeoｆRｃｖWinｄｏw,butcongesｔｉoncｏntrolbythetraｆficoｎtｈeliｎkＢconｇestioncｏntrollimiｔsitsratebythesiｚｅｏfRｃvWinｄow，ｂｕtfｌowcontrｏlbytheｔrａｆficｏntｈｅlｉnkCfｌｏwcｏntrolmainｌyisaｃcｏmpliｓheｄbythesendｅr,bｕtｃｏngestionｃｏｎtｒｏlｂythereceiver.Dflowconｔroｌmａｉnlyｉｓａccomplisｈｅdbytheｒeceivｅr,butcoｎgestionｃoｎtroｌｂｙthｅｌiｎk.99.Thｉsjobofdeliverinｇtｈｅdatainａt(yī)raｎｓpoｒｔ-lａｙeｒsegｍenｔｔｏtheｃorrｅctsｏｃkｅtiｓcalled_＿_(dá)_.AmultｉplｅxｉngＢde-multiplexiｎgＣforwaｒdinｇＤroｕtiｎg1０0．ＩｆwｅdefｉneNtｏｂethewindｏwｓize,basｅtobetｈesｅqｕeｎceｎuｍbeｒofｔhｅoldestｕnａcknoｗlｅdｇedpａckｅt,ａndnext-sｅq-numｔobetｈｅｓmallｅstunusｅｄsｅqｕｅｎcenumber,ｔheｎtheinterｖaｌ［bａse,ｎｅｘtseｑｎum-１]correspondsｔopacketthａｔ_＿_(dá)＿．AcａnbesentimｍｅdiatelyBhaｖealreadybeｅntransmｉtteｄａndａcknoｗｌｅdgedCcannoｔｂｅusedDhaｖｅbｅenｓentｂuｔｎoｔyetacｋｎowｌedgeｄ101._＿＿＿aｒethetｗoｔypesoftranｓporｔserviｃesthattheInterｎｅtｐrovidestｏｔｈeappliｃatiｏｎs.AＴCPandUＤPＢcｏｎnectioｎ－ｏrientedａnｄcoｎnecｔionlessｓerviｃeCTＣPandＩPＤreliabｌedａｔatransfｅraｎdfｌｏwconｔrｏl１02．Inｔｈefoｌlｏwingdｅscｒipｔionsａboｕtpｅrsiｓtentｃonｎecｔｉoｎ，ｗhｉchoｎeisnｏｔcｏｒrｅｃｔ?ＡThｅsｅｒveｒleavｅstheTCPconnｅctiｏｎopenaｆtersendinｇaresponｓeBＥachTＣPcｏnnectionｉscｌｏｓeｄafteｒtheseｒversｅndｉngoneｏbjｅcｔCＴherｅaretwoｖersiｏnｓoｆpersｉsｔentcｏｎnectｉon:witｈouｔpipeliniｎgandwithpipeliｎｉｎgDThｅdefaｕltmoｄeofHTＴＰusespersistentconneｃｔionwithpipelininｇ１0３.ＴhefiｅｌdｏfLengthinUDPｓegmenｔspecｉfiｅsｔｈeｌeｎgthof_＿_(dá)_.ＡｔheUDＰsegmeｎt,noｔiｎcludinｇtｈeheａderBtｈeUDPseｇment，inｃludiｎgtheheaderCtｈeＵDPsｅgmｅnｔ’ｓheaderDｔｈｅＬengthfｉeｌd1０4.InTCPsegmeｎthｅaｄer，whicｈfieｌdcanｉmｐlementｔhｅrｅliａbledatatraｎsｆer？Asｏurceｐortnｕmbｅrａnｄdｅｓtｉnａt(yī)ionpｏrtnｕmｂerBｓｅqｕeｎcenumberａndACＫnumberCurgｅｎｔdａt(yī)ａpoiｎtｅrDＲeｃeｉvewindow105.InthefolｌｏwingfourdｅｓｃｒｉptｉoｎsａboｕtＴCPcoｎneｃtionmａnａgement,whiｃhoｎeiｓnotcorreｃt?AEiｔheroｆthetwoprocessｅsparticipatingiｎaTＣＰconnectionｃaｎeｎdthecｏnneｃtioｎBＩftｈｅFINｂitisｓetｔo1,itｍeansｔhatitwａｎｔstoclosetheｃonｎeｃtioｎCInthefiｒsｔtwｏstｅpｏfthｅｔhree－wayｈａndshake，tｈｅｃlieｎtaｎdｓerverrａｎdomｌｙchoosｅaｎiｎitialsequeｎcｅｎumｂerDIｎｔhｅtｈreeseｇｍeｎtsoｆthetｈｒee－wayhanｄsｈake,theSYＮbiｔmｕｓtbesｅtto1１０6．SuｐposehoｓtAsｅnｄsｔwoTCPsegmentsbａcｋtobａcｋtoｈostBoveｒaTCPｃoｎｎection.Ｔhｅfｉrｓtｓegmentｈaｓsｅquencenumber4２，anｄtｈeseconｄhassｅquencenumber１10．Ｉfthe1sｔislｏｓtａnd２ndarriｖesathoｓtB.Whａt(yī)wilｌｂｅtｈeacknowledgmentnumbｅr？A43ＢACK42C109DACK1１０ConsidｅrsendinｇａnobjectoｆsizｅO=50０,000ｂytｅsfｒｏmservertoｃｌient.LeｔS=５00ｂyｔesaｎｄＲTT＝０.2ｓ.Suｐposethetrａnspｏrtpｒotoｃolｕsｅsstatiｃｗinｄoｗswｉtｈｗindｏwsｉze5．Foraｔrａｎsｍiｓsionrａt(yī)eof1０0Ｋbpｓ,determｉnｅtheｌatenｃｙforｓｅnｄingｔｈｅwｈoｌｅｏbｊｅct.ＲｅcallｔhenumberofwiｎｄowｓK=O/ＷS），andthｅreｉsK-1sｔalｌeｄstａｔｅ(ｔｈａt(yī)isｉdletiｍegaｐs).2．ConsidertｈefolｌowｉnｇpｌｏtofTCＰcoｎgestiｏnｗｉndowsizｅaｓafunｃｔionoftiｍｅ.141418026300026481012162022