计算机网络原理期末试卷2012级文档格式.docx
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A. 223.1.1.1 B.191.1.1.1 C.192.1.1.1 D.228.1.1.1
Ⅱ、Fillinblanks(1pointseachblank,total5points)
1.Coaxialcable,光纤andradioarethephysicalmediathatnetworkcanrunover.
2.IPaddressand端口号areusedbyaprocessrunningononehosttoidentifyaprocessrunningonanotherhost。
3.Considersendinga3000bytedatagramintoalinkthathasanMTUof500bytes.Howmanyfragmentsaregenerated7.
4.Therearetwobroadclassesofpacket-switchednetworks:
virtualcircuitand数据报network.
5.Abittimeisequalto1/10^7secondsfora10MbpsEthernet.
Ⅲ、Trueorfalse(1pointsforeachitem,total10points)
1.TheData:
headerintheHTTPresponsemessageindicateswhentheobjectintheresponsewaslastmodified. (F)
2.ThereceivewindowsizeofGBNprotocolisgreaterthan1. (F)
3.LinklayerprotocolisimplementedbyEthernetAdapter(书上写的是Networkinformationcard,NetworkAdapter)(以太网适配器,网卡)inEthernetNetwork.(T)
4.ARPtablesinnodesareestablishedbyself-learningthemselves(不是self-learning). (F)
5.TheslottedALOHAprotocolmakesmoreefficientinusingofthenetworkbandwidththanthepureALOHAprotocol. (T)
6.TheOSPFisarouteprotocolrelatedtodistancevectorroutingalgorithm. (F)
7.ThePPPoEisaPPP(PtoPProtocol)protocolthatitrunsoverEthernet. (T)
8.TheUDPheaderchecksumisrecomputedateveryrouters. (F)
9.TherearenocollisionsinCSMAprotocolbecauseithasdetectedthatthechannelisidlebeforetransmitsframe. (F)
10.Ingeneral,efficiency(效率)oftheCSMAprotocolchannelisbetterthantheSlottedALOHA.
(T)
Ⅳ、Pleaseanswerfollowingquestion(total30points)
1.WhatarethefivelayersintheInternetprotocolstack?
Whataretheprincipalresponsibilitiesforeachoftheselayers?
(5points)
1.应用层:
应用层是网络应用程序及其应用程协议停留的地方;
2.运输层:
运输层提供了在应用程序端点之间传送应用层报文的服务;
3.网络层:
因特网的网络层负责将称为数据报的网络层分组从一台主机移动到另一台主机;
4.链路层:
链路层将网络层传来的数据报沿着路径将数据传递给下一个结点;
5.物理层:
物理层的任务是将链路层传来的帧中的数据一个比特一个比特从一个节点移动到下一个结点;
2.Whichprotocolsareinter-ASsandintra-ASsprotocolsrespectively(各自的)usedintheInternet(5points)
Inter-ASs:
OSPF,BGP
Intra-Ass:
RIP,OSPF,IGRP
3.Considerthegenerator,G=1001,andsupposethatDhasthevalueof11001001.WhatarethebitsofCRCR?
WhatisthedatafortransferringwithCRCcode?
(5points).
011,11001001011
4.UDPandTCPuse1scomplementfortheirchecksums.Supposeyouhavethefollowingthree8-bitbytes01101010,01001111,01110011.Whatisthechecksumofthese8-bitbytes?
01101010
01001111
--------------------
10111001
01110011
---------------------
100101100
1
----------------------
00101101
5.WhatisthedifferentbetweenMACaddressandIPaddress?
mac是在在生产是就确认的,由网卡生产厂家烧入网卡的EPROM(一种闪存芯片,通常可以通过程序擦写),它存储的是传输数据时真正赖以标识发出数据的电脑和接收数据的主机的地址。
IP地址就是给每个连接在Internet上的主机分配的一个32bit地址。
32-bitIPaddress:
network-layeraddress
usedtogetdatagramtodestinationIPnetwork
MAC(MediaAccessControlorLANorphysicalorEthernet)address:
usedtogetframefromoneinterfacetoanotherphysically-connectedinterface(samenetwork)
48bitMACaddress(Ethernet)burnedintheadapterROM
Ⅴ、Comprehensiveproblems(total45points)
2.Accordingtothenetworkshownbelow,pleaseanalyzehowthelink-statealgorithmbuildstheroutingtableatnodeD.(15points)
Answer:
(1)ComputingtheshortestpathfromDtoallothernetworknodesaccordinglink-statealgorithm
N’
D(A),p(A)
D(B),p(B)
D(C),p(C)
D(E),p(E)
D(F),p(F)
D
8,D
∞
2,D
DE
4,E
3,E
DEC
6,C
9,C
DECB
DECBA
DECBAF
第11页,共6页
(2)DvectorandpvectorinnodeD(3)forwardingtableinD
D_
A
B
C
E
F
D(j)
6
4
3
2
9
p(j)
Destination
link
(D,E)
3.Pleaseanswerthefollowingquestions.(9points)
(1)ConsiderthefollowingHTTPGETmessage.Answerthefollowingquestions,indicatingwhereinthemessagebelowyoufindtheanswer.(4points)
GET/info/2012-10-18/0-1-411.html
http/1.1
Host:
User-agent:
Mozilla/4.0
Accept-language:
en
Keep-Alive:
300
Connection:
keep-alive
<
cr>
lf>
Questions:
a.WhatistheURLofthedocumentrequestedbythebrowser?
由第一行可得URL字段为
b.WhatversionofHTTPisthebrowserrunning?
由第一行的http/1.1可得知版本为HTTP1.1
c.Doesthebrowserrequestanon-persistentorapersistentconnection?
由Connection:
keep-alive可得知请求的为持久连接
d.Whatisdomainnameoftheserver?
由Host:
可得知domainname为
(2)ThetextbelowshowsthereplysentfromtheserverinresponsetotheHTTPGETmessageinthequestionabove
(1).Pleaseexplainthemeaningandfunctionofthelinedenotedbynumbersfrom①to⑤.(5points)
HTTP/1.1200OK ①
Content-Length:
19572 ②
Content-Type:
text/html
Last-Modified:
Sun,30Sep201207:
23:
15GMT ③
Accept-Ranges:
bytes
Server:
Microsoft-IIS/6.0
X-Powered-By:
ASP.NET
Date:
Thu,25Oct201221:
26:
48GMT ④
Keep-Alive ⑤
!
DOCTYPEhtmlPUBLIC"
-//W3C//DTDXHTML1.0Transitional//EN"
http:
//www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"
>
htmlxmlns="
http:
//www.w3.org/1999/xhtml"
head>
Muchmoredocumenttextfollowinghere(notshown)>
……
:
指明服务器使用的协议是HTTP1.1并且一切正常
表明被发送对象的字节数
指示对象创建或者最后被修改的时间
指示服务器产生并发送该响应报文的日期和时间
通知客户机收到报文后仍然保持连接
一、Choosethebestanswer(10problems,1pointseach,total10)
1.Auserentersintheaddresslineofabrowser.Whichstatementistrue(A)
A.The"
http"
portionindicatestheprotocolthatisbeingused.
B.The"
web1.htm"
portionisthespecificservicename.
C.TheretrievedwebpagewillbedisplayedinURLcode.
D.The"
"
isthenameofthewebpagefilethatiscalled.
2.MIMEistheSMTP’sextensiontotransmit(C)
A.textdataB.picturedata C.nonASCIIdata D.videodata
3.Inthefollowingpresentationaboutrouter(Ab)iswrong.
A.separatecollisiondomains
B.workindatalinklayer
C.separatebroadcastdomains
D.providebestpathtodestination
4.( A)isadynamicmappingprotocolinwhichphysicaladdressisfoundforagivenIPaddress.
A.ARP B.RARPC.ICMPD.Noneoftheabove
5.BelowarefourTCPpacketscapturedonthenetworkatdifferenttime,WhichonesbelongtothesameTCPconnection?
(C)
(1) (3)
src-address:
34.198.10.3
dest-address:
101.124.102.32
src-port:
3241
dest-port:
5432
seq-num:
2000
ack-num:
0
...
101.124.132.200
2000
1
1
2001
2001
(2) (4)
A.
(1)and
(2) B.
(2)and(3)C.(3)and(4)D.(4)and
(1)
6.Theprotocolsbelow,whichisnocollision(d)
A.CSMA B.ALOHA C.CSMA/CD D.TOKENRING
7.ForEthernet,ifanadapterdeterminesthatdestinationMACaddressofaframeithasjustreceivedisnotequaltotheadapter’sMACaddress()
A.itdiscardstheframewithoutsendinganerrormessagetothenetworklayer
B.itsendsaNACK(notacknowledgedframe)tothesendinghost
C.itdeliverstheframetothenetworklayer,andletsthenetworklayerdecidewhattodo
D.itdiscardstheframeandsendsanerrormessagetothenetworklayer
8.InCSMA/CD,afterthe