1、精選優質文檔傾情為你奉上精選優質文檔傾情為你奉上專心專注專業專心專注專業精選優質文檔傾情為你奉上專心專注專業四 川 大 學 期 末 考 試 試 題（A）（2006 2007 學年第 2 學期）課程號： 課序號：0 6 課程名稱：計算機網絡與通信 任課教師： 等 成績：適用專業年級： 04 學生人數： 印題份數： 學號： 姓名：考 試 須 知四川大學學生參加由學校組織或由學校承辦的各級各類考試，必須嚴格執行四川大學考試工作管理辦法和四川大學考場規則。有考試違紀作弊行為的，一律按照四川大學學生考試違紀作弊處罰條例進行處理。四川大學各級各類考試的監考人員，必須嚴格執行四川大學考試工作管理辦法、四川大

2、學考場規則和四川大學監考人員職責。有違反學校有關規定的，嚴格按照四川大學教學事故認定及處理辦法進行處理。一、英譯漢（10分）略PDA 2. RFC 3. IP 4.CIDR 5.URLCRC 7. CSMA/CD 8. ARQ 9. RIP 10.MSS 二、單項選擇題 （每小題l分，共30分）1. DSL divides the communication link between the home and the ISP into three nonoverlapping frequency bands, a upstream channel is in _A_.A)50 kHz to 1

3、MHz band B) 1MHz to 2MHz bandC)4 kHz to 50kHz band D) 0 to 4kHz band2. As a data packet moves from the upper to the lower layers, headers are A .A) Added; B) subtracted; C) rearranged; D) modified3. What is the main function of the network layer? DA) node-to-node delivery; B) process-to-process mess

4、age deliveryC) synchronization; D) updating and maintenance of routing tables4. Which of the following is the default mask for the address 01? BA) ; B) ; C) ; D) 555. A router reads the address on a packet to determine the next hop. AA) IP ; B) MAC; C) source; D)ARP6 . Which device cant isolates the

5、 departmental collision domains. AA) Hub; B) switch; C) router; D) A and B7. Input port of a router dont perform _D_ functions.A) the physical layer functions B) the data link layer functionsC) lookup and forwarding function D) network management8. HTTP has a mechanism that allows a cache to verify

6、that its objects are up to date. The mechanism is DA) persistent connections B) cookies C) Web Caching D) conditional GET9. A protocol layer can be implemented in _D_.A) software B) hardware C) a combination of the software and hardware D) All of the above注：1試題字跡務必清晰，書寫工整。 本題 4 頁，本頁為第 1 頁 2 題間不留空，一般

7、應題卷分開 教務處試題編號： 3務必用A4紙打印 10. A protocol has three important factors, they are_A_.syntax, semantics, order B) syntax, semantics, layersyntax, semantics, packet D) syntax , layer, packet 11. There are two broad classes of packet-switched networks: datagram networks and virtual-circuit networks. The vi

8、rtual-circuit networks forward packets in their switches use _D_. A) MAC addresses B) IP addresses C) e-mail addresses D) virtual-circuit numbers12. TCP service model doesnt provide _D_service. A) reliable transport service B) flow control service C) congestion-control service D) guarantee a minimum

9、 transmission rate service.13. Usually elastic applications dont include_B_.A) Electronic mail B) Internet telephonyC) file transfer D) Web transfer 14. A user who uses a user agent on his local PC receives his mail sited in a mail server by using _B_ protocol.A)SMTP B) POP3C)SNMP D) FTP15. Consider

10、ing sliding-window protocol, if the size of the transmitted window is N and the size of the receiving window is 1,the protocol is B A) stop-and-wait protocol B) Go-Back-N protocol C) selective Repeat protocol D) alternating-bit protocol16. which IP address is effective_B_.A) 202,131,45,61 B) C) 192.

11、268.0.2 D) 2217. if IP address is 3, subnet mask is ,then subnet prefix is_D_ A) B) C) 3 D)18.The command Ping s implemented with _B_messagesA) DNS B) ICMPC) IGMP D) RIP19. Which layer-function is mostly implemented in an adapter? _A_A) physical layer and link layer B) network layer and transport la

12、yerC)physical layer and network layer D) transport layer and application layer20. If a user brings his computer from Chengdu to Peking, and accesses Internet again. Now, _B_ of his computer needs to be changed. A) MAC address B) IP addressC) e-mail address D) user address三、填空題 （每空1分，共22分(注意：所有填空題不能寫

13、中文，否則中文答案對的情況下扣0.5分) 1. link-layer address is variously called a LAN address, a MAC address, or a physical address.2 In the layered architecture of computer networking, n layer is the user of n-1 layer and the service provider of n+1 layer.A) n B) n+3 C) n+1D) n-1注：1試題字跡務必清晰，書寫工整。 本題 4 頁，本頁為第 2 頁 2

14、題間不留空，一般應題卷分開 教務處試題編號： 3務必用A4紙打印 AprocessingBAprocessingB3. Suppose that Host A has established a connection to a process in the server. Please fill in the segments containing data that the client and server hosts can send to each other.Then Host A Host BIf Host A Then Host A Host BIf Host A Host BS

15、ource port =13 Dest port =21 Sequence number=1235Acknowledgment number=67905SYN=0ACKReceive windowChecksumNIL 1000 bytes data From above figure ,the window size of the segments is 216.4.Suppose a user sitting in a home network behind host requests a Web page on some Web server(port 80) with IP addre

16、ss 56,please according the NAT translation table at the NAT router,fill in datagram that include port numbers as well as IP addresses.（有IP缺端口號一個扣0.5分 ）NAT transtation tableWAN sideLAN side0, 5001, 1024 Source addr=,1024Source addr=,1024Dest addr=56,80S =0,5001Dddr=56,80S addr=56,80D addr=0,50010S ad

17、dr=56,80D addr=,1024Source port =21 Dest port =13 Sequence number=6790Acknowledgment number=22355SYN=0ACKReceive windowChecksumNIL 1000 bytes data 5.Summary of reliable data transfer mechanisms and their use, as show below. Please fill in transfer mechanisms. MechanismUseChecksumUsed to detect bit e

18、rrors in a transmitted packet.Sequencenumber Used for sequential numbering of packets of data flowing from sender to receiver.Acknowledgment（或ACK）Used by the receiver to tell the sender that a packet or set of packets has been received correctly.Countdown timerUsed to timeout/retransmit a packet, po

19、ssibly because the packet (or its ACK)was lost .Window,pipelinlingThe sender may be restricted to sending only packets with sequence numbers that fall within a given range.四、判斷題（每小題1分，共10分）The services of TCPs reliable data transfer founded on the services of the unreliable data transfer. Any protoc

20、ol that performs handshaking between the communication entities before transferring data is a connection-oriented service. HOL blocking occur in output ports of router.Socket is globally unique.SMTP require multimedia data to be ASCII encoded before transfer.The transmission delay is a function of t

21、he distance between the two routers. IP address is associated with the host or router. SO one device only have one IP address.8. In packet-switched networks, a sessions messages use the resources on demand, and Internet makes its best effort to deliver packets in a timely manner. 9. UDP is a kind of

22、 unreliable transmission layer protocol, so there is not any checksum field in UDP datagram header. 10. Forwarding table is configured by both Intra and Inter-AS routing algorithm 五、計算題 (28 points)Consider the following network. With the indicated link costs, use Dijkstras shortest-path algorithm to

23、 compute the shortest path from V to all network nodes(8分)yy421133241211wx925ustvzStepND(t),p(t)D(U),p(u)D(s),p(s)D(w),p(w)D(x),p(x)D(y),p(y)D(z),p(z)1v9,v5,v1,v3,v2,v2vw9,v4,w2,w2,v3vwx9,v4,w2,v4vwxy6,y4,w13,y5vwxyu6,y8,u13,y6vwxyut7,t8,t7vwxyuts8,t8vwxyutsz9So: the shortest path from v to t is vyt

24、 ; the shortest path from v to u is vwu; the shortest path from v to s is vyts. the shortest path from v to w is vwthe shortest path from v to x is vwx the shortest path from v to s is vy. the shortest path from v to z is vytznote:如果只有列表，沒有最短路徑的結論扣3分2. Suppose a ISP has been allocated the address block /24, now if the ISP wants to divide its address block into 6 equal-sized subnet address blocks, and each subnet could include 16 hosts.Please determine the length of subnet portion of address.(namely, how many bit