計算機網(wǎng)絡(luò)與通信期末考試_2009A_答案

1、四川大學(xué)期考試試題（A）閉卷(20082009學(xué)年第2學(xué)期)任課教師：等成績:姓名：課程號：30306230課序號：07課程名稱：計算機網(wǎng)絡(luò)與通信適用專業(yè)年級：05學(xué)生人數(shù)：印題份數(shù)：學(xué)號：考試須知四川大學(xué)學(xué)生參加由學(xué)校組織或由學(xué)校承辦的各級各類考試，必須嚴格執(zhí)行四川大學(xué)考試工作管理辦法和四川大學(xué)考場規(guī)則。有考試違紀作弊行為的，一律按照四川大學(xué)學(xué)生考試違紀作弊處罰條例進行處理。四川大學(xué)各級各類考試的監(jiān)考人員，必須嚴格執(zhí)行四川大學(xué)考試工作管理辦法、四川大學(xué)考場規(guī)則和四川大學(xué)監(jiān)考人員職責(zé)。有違反學(xué)校有關(guān)規(guī)定的，嚴格按照四川大學(xué)教學(xué)事故認定及處理辦法進行處理。第一題第二題第三題第四題第五題總分、英譯

2、漢（10分）1.ADSL非對稱數(shù)字用戶線路2.Packetswitching分組交換3.PPP點到點4.DHCP動態(tài)主機配置協(xié)議5.PDU協(xié)議數(shù)據(jù)單元6.MIME用途互聯(lián)網(wǎng)郵件擴展7.IMAPInternet消息訪問協(xié)議8.NAT網(wǎng)絡(luò)地址轉(zhuǎn)換9.ICMPInternet控制信息協(xié)議10.ARP地址解析協(xié)議、單項選擇題（每小題1.5分，共30分）1. AisaCircuit-switchednetwork.A.TDMB.DatagramnetworkC.InternetD.virtualcircuitnetwork2. Thestore-and-forwarddelayisDA.processi

3、ngdelayB.queuingdelayC.propagationdelayD.transmissiondelay3.Whichisnotthefunctionofconnection-orientedservice?CA.flowcontrolB.congestioncontrolC.errorcorrectionD.reliabledatatransfer4. TheIPprotocolliesinCA.applicationlayerB.transportlayerC.networklayerD.linklayer5. WhichofthefollowingisthePDUforapp

4、licationlayer_BA.datagram;B.message;6. bandwidthisdescribedin_B_A) BytespersecondC)megabitspermillisecondC.frame;D.segmentB) BitspersecondD)centimeters7. AuserwhousesauseragentonhislocalPCreceiveshismailsitedinamailserverbyusing_Bprotocol.A)SMTPB)POP3C)SNMPD)FTP8. Asadatapacketmovesfromthelowertothe

5、upperlayers,headersareB.A)Added;B.subtracted;C.rearranged;D.modified9. InTCP/IPstack,thetransportlayerbuildstheconnectionbyC一A)slowstartB)negotiationC)threehand-shakingD)slidingwindow10. ThemainfunctionoftransportlayeristoprovideCdatadelivery.A)nodetonodeB).pointtopointC).processtoprocessD).neighbor

6、toneighbor11. InTCP/IPmodel,dataunitsfromapplicationlayertodatalinklayerareB.A) messagedatagramframesegmentB) messagesegmentdatagramframeC) segmentdatagramframemessageD)datagrammessageframesegment12. .ThedefinitionofreliabledeliveryincludesD.A).Error-freedeliveryB).ReceiptofthecompletemessageC)In-or

7、derdeliveryD).Alloftheabove13. ThetracerouteisimplementedwithBmessagesA)DNSB)ICMPC)ARPD)RIP14. FragmentswhicharesmallerIPdatagramsneedtobereassembleattheBA)thedestinationrouterB)thedestinationhostC)thenextrouterD)anyrouterandhost15. Whichroutingprotocolisthedefectofstandardinter-ASroutingprotocolint

8、oday'sInternet._DA)RIPB)OSPFC)IGPD)BGP16. Thevirtual-circuitnetworksforwardpacketsintheirswitchesuse_D.A)MACaddressesB)IPaddressesC)e-mailaddressesD)VCnumbers17. packet-switchingtechnologiesthatusevirtualcircuitsinclude_D:A)X.25,IPB)X.25,framerelay.C)IPX,IPD)IP,TCP18.Therearetwobroadclassesofpac

9、ket-switchednetworks:datagramnetworksandvirtual-circuitnetworks.datagramnetworksforwardpacketsintheirswitchesuse_B.A)MACaddressesB)IPaddressesC)e-mailaddressesD)virtual-circuitnumbers19. .ifahostwantstoemitadatagramtoallhostsonthesamesubnet,thenthedatagramstinationIPaddressisBA)B)255.25

10、5.255.255C)54D)20. HubfunctionisintheAlayer.A)physical;B)datalink;C)Network;D)aandb三、填空題（每空1分，共20分）1. Internetprovidesboth_connection-orientedandconnectionlessservicestoapplications2. Internetuses_packetswitching_ratherthancircuit-switchingtechnology.3. Electronicmailincludingu

11、seragentsmailserversandSMTPthreemajorcomponents.4. Aprocessisidentifiedbyipaddressaswellasportnumber.5. Twoimportantnetwork-layerfunctioncanbeidentified:forwarding,routing.6. Networklayerserviceshandledatatransferbetweenhosts,transportlayerserviceshandledatatransferbetweenprocesses7. AnARPrequestisb

12、roadcasttoallhostandanARPreplyis_unicast_onehost；8. Alink-layeraddressisvariouslycalleda_lanaddress,orphysicaladdress,or_MAC_address.9. Datalinklayerpacketisframe10. SupposethatHostAhasestablishedaconnectiontoaprocessintheserver.Pleasefillinthesegmentscontainingdatathattheclientandserverhostscansend

13、toeachother.Sourceport=1300Destport=21Sequencenumber=1235Acknowledgmentnumber=67905SYN=0ACKReceivewindowChecksumNIL1000bytesdata+HostB四、判斷題（每小題1分，共10分）IfHostASourceport=_21_Destport=_1300_Sequencenumber=6790_Acknowledgmentnumber=2235_5SYN=0ACKReceivewindowChecksumNIL1000bytesdataThenHostAHostB1. The

14、internetapplicationssuchasSMTP,HTTP,TELNETusUDP,theinternet'sconnectionless-orientedserviceF2. HTTPismainlyapushprotocolandSMTPismainlyapullprotocolF3. ThetimerequiredtopropagatefromthebeginningofthelinktoarouteristhepropagationdelayT4. FTPsenditscontrolinformationout-of-bandT5. linklayeraddress

15、isIPaddressF6. AnARPresponsesentwithinaframewithaspecificdestinationMACaddressT7. AnIPaddressistechnicallyassociatedwiththehostorrouterF8. Adistance-vector(DV)algorithmcomputestheleast-costpathbetweenasourceanddestinationusingcomplete,globalknowledgeaboutthenetworkFtmakesits9. Devicesinasubnetcanphy

16、sicallyreacheachotherwithoutinterveningrouterT10. .Inpacket-switchednetworks,asession'smessagesusetheresourcesondemand,andInternebestefforttodeliverpacketsinatimelymannerT-pathalgorithmtosshortest五、計算題(30points)1. considerthefollowingnetwork.Withtheindicatedlinkcosts,useDijkstracomputetheshortes

17、tpathfromWtoallnetworknodes.10分1)2)3)4)howmanybitsshouldbeextend?(2Pleasewriteoutthesubnet2#Pleasewriteoutthesubnet2#Pleasewriteoutthesubnet2#snetwork)preflix(ubnetmask.(2分)broadcastad)ress.(2srangeofhstaddress.StepN，D(x),p(x)D(V),p(v)D(U),p(u)D(y),p(y)D(t),p(t)D(s),p(s)1W3,w1,w4,woooooo2wv3,w2,v4,v

18、8,voo3wvu3,w4,v5,u7,u4wvux4,v5,u7,u5wvuxy5,u7,u6wvuxyt6,t7wvuxyts最短路徑：WXWVWVYWVUWVUTWVUTS表格8分最短路徑2分2. SupposeaISPhasbeenallocatedtheaddressblock/24,nowiftheISPwantstodivideitsaddressblockinto6equal-sizedsubnetaddressblocks,andeachsubnetcouldinclude25hosts.PleaseutilizeCIDRizedaddresses,determinethelengthofsubnetportionofaddress.(namely,答案：1227位prefix或子網(wǎng)右擴3位4,2455-4注：1試題字跡務(wù)必清晰，書寫工整。3Considersendinga3,000-bytedatagramintoalinkthathasanMTUof1500bytes