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

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Whiｃh

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UDP

36.Ｉfanaｐｐliｃationdeveloｐerchoｏｓｅｓ_＿_＿protocol，tｈentｈｅapplｉｃaｔionprｏｃeｓsiｓalmｏstdｉrectlytaｌｋｉnｇwiｔhIP.AHＴTPBRIPCCSMＡ/CDDUDP37._＿_＿maintainsconnectiｏn－ｓtatｅintheeｎdsyｓtems.Thisconneｃtionsｔａteiｎcludｅｓrｅceiveａndsｅndｂuffers,congeｓtｉon-controｌｐaramｅteｒs，aｎdｓeｑｕeｎcｅaｎｄackｎowleｄgmｅntnｕmｂeｒpaｒametｅrs.AＵDP BTCP? CDＮS DHTTP38.ＴhehostｔhａtinitｉaｔesthesessioninｔｈeInternｅtiｓlabeledaｓ＿___.Aserver?Bｕｓerａgeｎｔ?Ｃcｌｉｅnｔ??Drouter3９.WｉthTCＰthｅｒeisno_＿__＿bｅtｗｅeｎsｅｎdinganｄreceiviｎgtranｓporｔ-layｅｒentiｔies．Aflowcｏｎtｒol BhandshakingＣ.coｎgesｔｉｏnｃoｎtｒoｌ ＤVＣsetuｐ40.ＴｈｅInterｎeｔ’ｓ_＿__ｓervicｅhｅlpspreventtheIｎｔｅrnetfｒomenterｉnｇastａtｅofgrｉdloｃｋ.Adａtagｒam? ? BｃongesｔｉoncontｒoｌCsｌidinｇｗiｎdoｗ? Dｔｉmeoｕtｅvent41.Conｎｅcｔioｎseｔｕpattｈetranｓpｏrtlaｙerinvolves_＿_＿.Ａｓerver ? ?BonlytｈｅtwoendsystｅmsCcｌｉeｎt ? Ｄｒｏｕｔer42.A____lａyｅｒpｒotoｃolｐrovidesfoｒlogiｃａlcommｕnicaｔiｏnｂｅtwｅenapｐlicａtｉｏns.AｔｒansｐoｒtBaｐplicatiｏnCｎetｗｏrkingDＭAC43.Ｉnｓtａticconｇｅstｉｏｎwindow,ｉfitsａｔｉsｆieｓW*S/R>RＴＴ+Ｓ/Ｒ，theＬａtenｃyｉs____.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?ＡThｅｖariａtionｓiｎtheSampleRＴTaresｍoothedｏutiｎthecomputａtiｏnofthｅEstimａtedRTTBＴhetimeoutshｏｕldbｅlesｓtｈantheconnectiｏn’sＲTTＣSuｐposｅthatｔhelasｔSamplｅRTTｉnａTCPconｎecｔionisequａlto1sec．TｈenｔｈeｃurrenｔvalueｏfTimeoｕｔIntervalwｉｌlnecｅssarｉlybｅ≥1secDSuppｏsethａｔthelastSaｍｐleRTTinaＴCPｃonｎectionｉｓｅｑualto１sｅc.ThentｈecuｒreｎtvalueofTimeoutＩnterｖalｗilｌnecesｓarilyｂe≤１seｃ４６.TheportｎumbeｒusedｂyＨTＴＰiｓ___＿.A80Ｂ２5C1１０Ｄ５３47.TｈepoｒｔnｕmberusｅdｂySMTPｉs_＿__.A80B25C1１０D534８.Thepoｒtnumbeｒusedbypop3iｓ＿___.A８0B2５C110Ｄ53４9.TｈepoｒｔnｕmberｕseｄbyDＮSis__＿_.A80B25Ｃ110D5３50.TheｐoｒtnumberusｅdbyＦTPｉs__＿_．Ａ２0and21B20C21D5351.AUＤＰsｏcｋetideｎｔiｆiｅｄbｙa___＿ｔuｐｌe(s).A2B４Ｃ1D3５２.ATCPsｏｃkeｔidentiｆｉedbya_＿__tｕｐlｅ(s)．A2B4Ｃ1D3５3.ＡTＣPsocketdｏｅsｎotincｌuｄe_＿__．ＡSourceMＡCaddｒessBSｏurｃeportnumberCDｅstinａｔionＩPaddｒessDDｅｓｔinａtｉonｐoｒｔｎumber5４.WhichoｆfolｌowiｎｇａｂoutUDPisnｏtcorｒｅct.ＡItisareｌiabledatａtｒａnsferpｒotocｏlＢIｔｉsｃoｎｎectiｏnｌessCnｏhaｎdｓhakingｂetｗeｅｎUDPsｅnder，receｉｖerDｉtｉsａbｅstefｆortserviceprotocol55．DNSｕsｅs_＿__sｅrvice.AＴCＰBUＤＰＣBotｈTCPaｎｄUＤＰDNｏneofabove56.WhｉchoffoｌｌowingaｂoｕtUDＰiscoｒreｃt？AFinerａｐplｉcａtion－lｅvelconｔrolovｅrwhａtdataissent，andwｈenBNocｏnｎｅctionｅstablishｍent(whichcanadddｅlaｙ)，sonｏdelayfｏｒeｓtaｂlishaconneｃtionＣNoconｎectiｏnstate（sｏ,UDPcaｎtｙpｉｃａllyｓｕppｏｒtmaｎyａcｔivｅcｌienｔs)DLａｒgepacketheaｄeｒoveｒｈｅad(１6-B）57．Ｓtｒｅａmiｎgmｅdiausｅsa____sｅrvicｅnormallｙ．ＡTCPBUDPCBothTCＰandUDPＤNonｅoｆａboｖe58．TheUDPheａderhaｓonｌy___＿ｆiｅｌｄs.A2Ｂ4Ｃ1Ｄ3５9.WhｉchｏfｔhefｏlｌowingｄoeｓnotｉncluｄｅdｉnUDPheａｄer．ASourcｅpｏｒtnumｂerBＤｅsｔｉnationporｔnumberＣChｅcksumDＳeｑueｎｃenuｍber６０.Wｈｉchofｔhｅfolｌowinｇｉsnoｔaｐiｐeliningprotocoｌ．ARdt1．0BGｏ-Bａｃk-NCＳｅlectｉｖerｅpeａtDTCP61.InthefｏllowingfouｒdeｓｃriptiｏnsaboutMＳＳａndMTU,ｗhichoneｉｓｎotcorrect？AＴheMＳSisthemａximｕmamountｏfapplｉcａtion-ｌayerdａtaiｎtｈeseｇｍentBThｅMSSｉsthemaximｕmｓiｚｅoftheTCPsegmeｎｔｉnclｕｄinｇhｅadｅrsCTheMSSisｔｙpicａｌlysｅｔbｙMＴUDTｈeMTUｍeanｓtheｌａrｇestlink-layerfｒame62．Tｈeｊｏbｏfgathｅｒingdataｃｈｕnkｓ,encapsulatｉｎgｅachdatａcｈｕnkwｉthheaderinfｏrｍationtocrｅatesｅgmenｔｓandpａsｓingthesｅgmｅntstoｔｈeneｔwｏrkiscalｌｅd____．AｍulｔｉpｌｅｘiｎgBde-multｉpleｘiｎgCｆｏrｗaｒｄｉngDrouｔｉng63.Inｔhefoｌlｏｗiｎgfourdeｓcriptionsａboutthereｌａtｉonsｈipbeｔｗeeｎthetranspｏrtlayerandｔhenｅtwｏrklａyeｒ，ｗhichoneｉsnｏｔcorrecｔ？AＴｈetranｓpｏrt-layerpｒotｏcｏlｐｒovideslｏｇicalcoｍｍunicationｂeｔweenｈostsBTｈeｔrａｎsport-laｙerprｏtocolｐrovidesloｇicalｃoｍmuniｃationbetweenpｒocｅssesCＴheｓeｒｖicｅsｔhatatransｐorｔ-lａｙerｐｒｏtoｃolcanｐroviｄeａreｏfteｎcoｎstｒaｉnｅdbythｅｓerviceｍodelｏｆtheneｔｗｏｒk-laｙｅｒｐｒotocolDＡcｏmputernetworkmaｙmakeavaｉlablemultipletransｐｏrtｐｒｏtｏｃoｌs６4.Suppｏsｅthefollｏwiｎgtｈrｅe8-bitbytes:010１0101，01１10000,01001１00.Whａt’ｓtｈe1scoｍplemenｔofthesumofｔｈese8-biｔbｙtｅs？Ａ０0010001B1１１０１10１C00０10010D1000100065.Ｔｈefollowiｎgfouｒｄｅｓcriptiｏnsabouｔmｕltiplｅｘingandde－muｌtiｐｌexing，whｉｃｈonｅｉｓcorrｅｃt?ＡAＵDPｓocｋetisiｄentｉfｉedｂyatｗo-tuplesｃonｓistｉngｏｆasouｒceportnｕmｂeranｄadestinaｔioｎportnｕmber．BIfｔwｏUDPsegｍenthaｖeｄｉffｅreｎtｓｏuｒceｐortｎumbeｒ，theｙmaybedｉrecteｄtothｅsａｍeｄestinaｔiｏnprocess．CIftwｏTCPｓegｍentswｉｔhｄiffeｒeｎtｓｏｕrｃeｐortnumber,tｈeｙmaybediｒｅｃtedｔothesamedestiｎationprocess.DIftwoTCPｓegmentswitｈｓａmedestinａtiｏnIPａddressaｎｄdestinatｉonportnｕｍｂｅr,theymusｔｂｅｔhesaｍｅTCＰｃｏnnｅction.66.UＤPanｄＴCＰbothhaｖethefieldｓeｘｃept＿_＿_.AｓourceportｎｕmbｅrＢdesｔinatioｎporｔnumbｅｒCｃhｅｃksuｍDrｅceiｖewindoｗ67.IｆweｄeｆineNtobetheｗinｄowsｉｚe,baseｔｏｂｅｔheｓｅqｕencenumberoftheolｄｅstuｎａｃknｏwlｅdgeｄｐacket,ａnｄnext-seq-nuｍtoｂethｅsmallｅｓｔｕｎｕseｄseqｕｅncｅnｕmber，tｈｅntｈeｉntｅｒｖal［ｎｅxtｓｅqnｕm,base＋N-1]correspondstoｐａckeｔthａt___＿.AcａnｂeｓentimmeｄiａtｅlｙＢhavｅalreadｙｂeｅｎtraｎsmiｔｔeｄaｎdaｃkｎowledgedCcannｏｔbeuｓedDhavebeｅnsｅntbutnotyｅtaｃｋnowlｅdｇed68.ＷhicｈofthｅfｏｌｌoｗｉngａｂouｔTＣPisｎotcorrecｔ?AIｔiｓacｏnnｅctiｏnｌessprotocoｌBPoiｎt-tｏ-poiｎtpｒotｏｃoｌCReliable,in-ｏｒderbytestｅamprｏtｏcｏｌＤＰipelinｅdｐrｏtocol69．ＷｈｉcｈoｆｔhefolｌｏwingａbｏutＴＣPiｓnotcｏrｒect?AＩtiｓａconnectionlesｓprｏtｏcoｌBfulldｕplexdatａtransferprotocolＣｃｏnｎectiｏn－oriｅntｅdprｏｔocolＤｆloｗconｔｒollｅｄpｒｏｔocol７0.Tｈemaximumamouｎtofｄatathatcanｂｅgrabbｅdandplacediｎａsegmentiｓlｉｍiｔｅdbytｈe____．AMaximｕmsegmentsiｚｅ(MSS)BＭTUCSequeｎceｎumberＤCheｃksｕm7１．ThｅＭSSiｓtyｐicallysｅtbyfirsｔｄeｔｅrｍinｉngtheｌeｎgtｈofthｅｌaｒgｅstｌink-ｌayerｆraｍetｈaｔcanbesentbyｔheloｃａｌsｅndingｈost（thesｏ-callｅd_＿__),andｔhｅnwｉllfｉｔintｏaｓiｎglelink-layerframe.AMaximuｍsegmeｎtｓiｚe(MＳS)BMTUCSequenceｎｕｍberＤChｅｃkｓuｍ７2.TheMＳSisｔheｍaxiｍuｍamoｕntof____lａyerdaｔaintｈesegｍent,notｔhｅmaｘｉmｕmｓizeoftｈeTCPsegｍentinｃludｉngheadｅrs.ＡＡｐpliｃationBTransportCNeｔworkingDLｉｎk73.Whｉｃｈoｆthefｏllｏwingfｉeldisｎｏｔuｓedｆorconnｅctiｏnsｅtuｐandteaｒdｏｗn？ASequeｎcenｕｍberBＴＳTＣSＹNDFIN74.＿___isｔｈeｂｙｔestreａmnumberｏffirｓtｂyteintheseｇｍｅｎt．AＳequｅncenｕmbｅrBＡCＫnｕｍberCCheｃkｓumＤｐoｒtｎumber75._＿__isthｅbｙtｅseqｕｅｎcenｕmbeｒｓofnextbyteexpectedfroｍotheｒsｉde.ASｅquencenuｍbeｒBＡCＫnuｍbｅrCChecksumDportnumｂeｒ７６.BｅｃaｕsｅＴCPoｎlｙackｎowledgesbｙtesｕｐtｏthefirstmｉssiｎgbytｅintheｓtｒeaｍ,ＴＣPissａiｄtｏｐrovide_＿__acｋｎｏwleｄgements.ＡＣumulatｉvｅBSeleｃtｉveCSinｇleDNｅgative７7．Ｆaｓtretranｓmitmｅａnsｉｎthecａseｔhaｔ_＿__dｕpliｃateACK-sarｅreceiｖｅd,theTCPsenｄerresendsegmentbeforetｉmerexpireｓ.A3B４C5Ｄ678.ＴCＰ＿___meaｎssenderwon’ｔoverflｏwｒｅceiver’sｂuffｅrbytraｎsmｉttｉnｇtoomuch,tｏｏfast.AFloｗｃoｎtｒｏｌBCongestioncｏｎtroｌCReliａbledatatransfｅrＤConnecｔion-oｒiｅｎteｄservice79.TCＰprovidesfｌowcoｎtrolｂyｈaｖiｎgtheseｎｄeｒmａｉntaｉnavariaｂｌeｃallｅｄthe_＿__．ARecｅivｅwinｄｏwBＣｏngｅstionwiｎdowCSlidiｎgｗinｄowDbuffｅr80.HoｗｄoesTCPsｅnｄerｐeｒceivecｏngesｔｉon?ＡTimｅoｕtB3dupｌicａtｅACK－sCBotｈAandBＤNoｎｅofabｏvｅ8１.Traｎｓｐtoｃｏｌsrｕnin_＿__.ＡServersBClｉentsCRoutersＤEｎdｓysｔemｓ82.WhiｃhoｆtheｆｏllowingservicｅsisnoｔｐroviｄeｄｂyTCP?ADelaｙguarａnteesandbandｗｉｄｔｈguaranteesBＲeliablｅdａtatransfersaｎdflowcontｒolsCCongesｔｉｏｎcontrolsDIｎ-oｒdｅrdaｔatｒaｎsferｓ8３.WｈichserｖｉcedoesUDPnotprovide?ＡmuｌtipleｘingＢｄe-mulｔｉpleｘinｇＣeｒror-deｔｅｃｔｉonＤｅｒｒor-corrｅctioｎ8４.TherearethreemaｊorｅvｅntsｒｅｌaｔeｄtoｄatatｒaｎsmｉsｓionandretranｓmisｓionｉntｈeTCPsｅnｄer,ｗhｉchoneiｓnotｉnit?ＡｄatareceiveｄｆrｏmａppｌｉcａtionabｏveBde-ｍultipleｘingsｅgmｅｎｔＣtiｍerｔimeoutDACKrｅｃｅipt85．ＷhｉｃhoｆtｈeｆｏlｌowｉnｇapplicationsnormａlｌyusesUDＰsｅrvｉceｓ?AＳMTPBStrｅａmｉnｇmｕltｉｍeｄiaCＦＴPDHTTP８6．WhicｈofthefｏllowｉｎgaboｕtＴＣPｃonnectioｎｉsｎotcorrect?AItisabroａdcaｓｔconｎecｔiｏnＢItiｓapoinｔ-to-poｉnｔｃoｎneｃｔｉoｎCItisapipｅlineｄconｎｅctionＤＩtｉsafｕlｌdｕpｌexｃonnectiｏn８7.ＴheSＹNsegmｅnｔｉsｕsedfor＿_＿＿.ATCPconnectionsｅtｕｐBTCＰｆlowcoｎｔrolＣTＣPcｏngｅsｔiｏncｏntｒoｌDＣloｓingaTＣＰconneｃｔioｎ8８.Whiｃhserviｃehｅlpsｐｒｅveｎtthｅiｎtｅｒnetfrｏmenｔｅringａstatｅofgrｉdｌock？AreｌｉaｂledatatｒansferBfloｗcｏntrｏｌCｃoｎgesｔｉoncontrｏlDhandｓhakinｇｐroceduｒe89．TheInteｒnｅt’s_____isｒespｏnsiblｅｆormｏvingpａｃkeｔsfｒoｍｏnehｏｓttoanｏther.AaｐplｉｃatioｎlayerBtransｐorｔlayerＣｎetｗoｒklayeｒDｌiｎklayerＩnｔhｅfｏllｏwingaｐｐｌicａtｉons,wｈichoｎｅisabａndwiｄｔh-sensitiveapplｉｃａtion?ＡE-mａilBwebapplｉcationＣreal-tiｍeauｄiｏDfｉletrａｎｓfeｒ91.Ｉnthefoｌｌowｉｎgappｌｉcations,whｉcｈonｅuseｓUDＰ？ＡE-ｍaiｌBweｂapplｉcａtionCfｉleｔransｆeｒＤDNS92.Iｎthｅfoｌｌowiｎgｆouｒｄescriptioｎｓ,ｗhiｃhoneiscorrect?AIfｏneｈｏｓt’stranｓpｏｒtlａｙeruｓesTCP,ｔｈenｉtsnｅtworｋｌａｙｅrmusｔｕsevirtuａｌ-circuｉｔnetｗｏrｋ．BDatａｇrａｍnｅtｗoｒｋpｒｏvｉdesｃonｎｅctｉoｎservｉcｅＣThetraｎｓport－layerｃoｎｎeｃｔｉonseｒviceisｉmplｅｍentedｉntheroｕterDThenetｗork-ｌayｅrcoｎnectioｎservicｅiｓimpｌementeｄiｎtheroｕtｅrａsweｌlａｓinthｅendｓysｔem.____ｉsasｐeeｄiｎg-ｍａｔchｉngｓervice－--maｔｃhｉnｇtｈeｒatewhichthesｅｎｄeriｓsendingagainsttheratｅaｔｗhｉchｔhｅreceｉｖingａpplicａtｉoniｓreadinｇ.AcｏngｅstionconｔrｏlBfｌowconｔrolＣslidiｎg-wｉndｏwcｏntｒolDvarｉablecｏntroｌ９4．InthefollｏwｉnｇfｏｕrdescripｔｉonsａboｕtRcv-Wiｎdow,wｈｉｃhonｅｉsｃorreｃｔ?AThesizｅoftｈeTＣPRcvWindoｗｎeverchangesthroｕghｏuｔthｅｄuraｔiｏnofthｅcｏnnectionＢTheｓｉzｅｏftheＴＣPRcvWindoｗwillcｈangeｗithｔhｅsizｅｏｆthｅTＣPRcvBufｆerＣＴhesizｅoｆthｅTCPRcvＷindoｗmuｓtｂelesstｈａnorequaltothｅｓｉｚeoftheTCPRcvBuffeｒDＳupｐoseｈosｔAｓendsafｉlｅtohｏｓtBoverａTＣPｃonnecｔiｏn,thenumberofuｎacknowlｅｄgedｂｙtestｈａｔAｓｅndscａnnｏtexceeｄtｈesizeｏftheｓizｅoftheＲcvWiｎdow．９５.Thereare6fｌagfｉeｌdｓ.Whiｃhoｎeistｏindicａtｅtｈａｔｔｈerecｅivｅrshoｕlｄpａsｓthedataｔotheupｐeｒlａyerimｍediaｔely?AＰＳHＢURGCACＫDRST９6.SupposｅthｅＴCＰrｅｃeｉverreｃeｉｖｅｓtheｓegmｅｎtthａtpaｒtiａllyorcompｌｅteｌｙfiｌｌsiｎgapinrｅcｅiｖeddａta，iｔwill____.AｉmｍediatelｙｓendAＣKBｉｍmediatelyseｎｄdupｌicateAＣKＣwaitsomｅｔimeforarrivａlofanoｔhｅrin-oｒderｓegmenｔＤsendsiｎglecumulａtivｅ９7.＿＿__＿iｍposeｓcｏｎstrainoｎtheｒａｔeatｗｈichaTCPｓendercanｓenｄｔraｆficｉnｔoｔhｅnetwｏｒk.AsｌidｉｎgｗiｎdowBconｇｅstioｎｗiｎｄowＣreceivewiｎdoｗDvarｉａbｌeｗindｏw9８.Fｌowcontｒolａndcongestｉoncｏntｒolaresａmｅａｔthattｈｅｙalｌliｍitthｅratｅｏfthesendeｒ，ｂutdｉｆferｉnthat＿_＿_.AｆlｏwｃonｔｒollｉmｉtsitsratebｙthesizeoｆRｃｖWinｄｏw,butcongesｔｉoncｏntrolbythetraｆficoｎtｈeliｎkＢconｇestioncｏntrollimiｔsitsratebythesiｚｅｏfRｃvWinｄow，ｂｕtfｌowcontrｏlbytheｔrａｆficｏntｈｅlｉnkCfｌｏwcｏntrolmainｌyisaｃcｏmpliｓheｄbythesendｅr,bｕtｃｏngestionｃｏｎtｒｏlｂythereceiver.Dflowconｔroｌmａｉnlyｉｓａccomplisｈｅdbytheｒeceivｅr,butcoｎgestionｃoｎtroｌｂｙthｅｌiｎk.99.Thｉsjobofdeliverinｇtｈｅdatainａtraｎｓpoｒｔ-lａｙeｒsegｍenｔｔｏtheｃorrｅctsｏｃkｅtiｓcalled_＿__.AmultｉplｅxｉngＢde-multiplexiｎgＣforwaｒdinｇＤroｕtiｎg1０0．ＩｆwｅdefｉneNtｏｂethewindｏwｓize,basｅtobetｈesｅqｕeｎceｎuｍbeｒofｔhｅoldestｕnａcknoｗlｅdｇedpａckｅt,ａndnext-sｅq-numｔobetｈｅｓmallｅstunusｅｄsｅqｕｅｎcenumber,ｔheｎtheinterｖaｌ［bａse,ｎｅｘtseｑｎum-１]correspondsｔopacketthａｔ_＿_＿．AcａnbesentimｍｅdiatelyBhaｖealreadybeｅntransmｉtteｄａndａcknoｗｌｅdgedCcannoｔｂｅusedDhaｖｅbｅenｓentｂuｔｎoｔyetacｋｎowｌedgeｄ101._＿＿＿aｒethetｗoｔypesoftranｓporｔserviｃesthattheInterｎｅtｐrovidestｏｔｈeappliｃatiｏｎs.AＴCPandUＤPＢcｏｎnectioｎ－ｏrientedａnｄcoｎnecｔionlessｓerviｃeCTＣPandＩPＤreliabｌedａｔatransfｅraｎdfｌｏwconｔrｏl１02．Inｔｈefoｌlｏwingdｅscｒipｔionsａboｕtpｅrsiｓtentｃonｎecｔｉoｎ，ｗhｉchoｎeisnｏｔcｏｒrｅｃｔ?ＡThｅsｅｒveｒleavｅstheTCPconnｅctiｏｎopenaｆtersendinｇaresponｓeBＥachTＣPcｏnnectionｉscｌｏｓeｄafteｒtheseｒversｅndｉngoneｏbjｅcｔCＴherｅaretwoｖersiｏnｓoｆpersｉsｔentcｏｎnectｉon:witｈouｔpipeliniｎgandwithpipeliｎｉｎgDThｅdefaｕltmoｄeofHTＴＰusespersistentconneｃｔionwithpipelininｇ１0３.ＴhefiｅｌdｏfLengthinUDPｓegmenｔspecｉfiｅsｔｈeｌeｎgthof_＿__.ＡｔheUDＰsegmeｎt,noｔiｎcludinｇtｈeheａderBtｈeUDPseｇment，inｃludiｎgtheheaderCtｈeＵDPsｅgmｅnｔ’ｓheaderDｔｈｅＬengthfｉeｌd1０4.InTCPsegmeｎthｅaｄer，whicｈfieｌdcanｉmｐlementｔhｅrｅliａbledatatraｎsｆer？AsｏurceｐortnｕmbｅrａnｄdｅｓtｉnａtionpｏrtnｕmｂerBｓｅqｕeｎcenumberａndACＫnumberCurgｅｎｔdａtａpoiｎtｅrDＲeｃeｉvewindow105.InthefolｌｏwingfourdｅｓｃｒｉptｉoｎsａboｕtＴCPcoｎneｃtionmａnａgement,whiｃhoｎeiｓnotcorreｃt?AEiｔheroｆthetwoprocessｅsparticipatingiｎaTＣＰconnectionｃaｎeｎdthecｏnneｃtioｎBＩftｈｅFINｂitisｓetｔo1,itｍeansｔhatitwａｎｔstoclosetheｃonｎeｃtioｎCInthefiｒsｔtwｏstｅpｏfthｅｔhree－wayｈａndshake，tｈｅｃlieｎtaｎdｓerverrａｎdomｌｙchoosｅaｎiｎitialsequeｎcｅｎumｂerDIｎｔhｅtｈreeseｇｍeｎtsoｆthetｈｒee－wayhanｄsｈake,theSYＮbiｔmｕｓtbesｅtto1１０6．SuｐposehoｓtAsｅnｄsｔwoTCPsegmentsbａcｋtobａcｋtoｈostBoveｒaTCPｃoｎｎection.Ｔhｅfｉrｓtｓegmentｈaｓsｅquencenumber4２，anｄtｈeseconｄhassｅquencenumber１10．Ｉfthe1sｔislｏｓtａnd２ndarriｖesathoｓtB.Whａtwilｌｂｅtｈeacknowledgmentnumbｅr？A43ＢACK42C109DACK1１０ConsidｅrsendinｇａnobjectoｆsizｅO=50０,000ｂytｅsfｒｏmservertoｃｌient.LeｔS=５00ｂyｔesaｎｄＲTT＝０.2ｓ.Suｐposethetrａnspｏrtpｒotoｃolｕsｅsstatiｃｗinｄoｗswｉtｈｗindｏwsｉze5．Foraｔrａｎsｍiｓsionrａteof1０0Ｋbpｓ,determｉnｅtheｌatenｃｙforｓｅnｄingｔｈｅwｈoｌｅｏbｊｅct.ＲｅcallｔhenumberofwiｎｄowｓK=O/ＷS），andthｅreｉsK-1sｔalｌeｄstａｔｅ(ｔｈａtisｉdletiｍegaｐs).2．ConsidertｈefolｌowｉnｇpｌｏtofTCＰcoｎgestiｏnｗｉndowsizｅaｓafunｃｔionoftiｍｅ.141418026300026481012162022