四川大学计算机网络与通信期末考试08-09A.doc

1、四 川 大 学 期 末 考 试 试 题（A） 闭卷（2008 2009 学年第 2 学期）课程号：30306230 课序号：0 7 课程名称：计算机网络与通信 任课教师： 成绩：适用专业年级：05 学生人数： 印题份数： 学号： 姓名：考 试 须 知四川大学学生参加由学校组织或由学校承办的各级各类考试，必须严格执行四川大学考试工作管理办法和四川大学考场规则 。有考试违纪作弊行为的，一律按照四川大学学生考试违纪作弊处罚条例进行处理。四川大学各级各类考试的监考人员，必须严格执行四川大学考试工作管理办法 、 四川大学考场规则和四川大学监考人员职责 。有违反学校有关规定的，严格按照四川大学教学事故认定

2、及处理办法进行处理。第一题 第二题 第三题 第四题 第五题 总分一、英译汉（10 分）1. ADSL 非对称数字用户线路 2. Packet switching 分组交换 3. PPP 点到点 4. DHCP 动态主机配置协议 5. PDU 协议数据单元 6. MIME 用途互联网邮件扩展 7. IMAP Internet 消息访问协议 8. NAT 网络地址转换 9. ICMP Internet 控制信息协议 10. ARP 地址解析协议二、单项选择题 （每小题 l. 5 分，共 30 分)1 A is a Circuit-switched network.A. TDM B. Datagra

3、m network C. Internet D. virtual circuit network 2The store-and-forward delay is DA. processing delay B. queuing delay C. propagation delay D. transmission delay3Which is not the function of connection-oriented service? CA. flow control B. congestion control C. error correction D. reliable data tran

4、sfer4The IP protocol lies in CA. application layer B. transport layer C. network layer D. link layer5Which of the following is the PDU for application layer_B_ .A. datagram; B. message; C. frame; D. segment6bandwidth is described in _B_A) Bytes per second B) Bits per secondC) megabits per millisecon

5、d D) centimeters7A 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) FTP 8As a data packet moves from the lower to the upper layers, headers are B .A)Added; B. subtracted; C. rearranged; D. modified9In TCP/IP stack, the

6、transport layer builds the connection by C A) slow start B) negotiation C) three hand-shaking D) sliding window10The main function of transport layer is to provide C data delivery.A) node to node B).point to pointC).process to process D).neighbor to neighbor 11In TCP/IP model, data units from applic

7、ation layer to data link layer are B .A) messagedatagramframesegmentB) messagesegmentdatagramframeC) segmentdatagramframemessageD)datagrammessageframesegment12The definition of reliable delivery includes D .A). Error-free delivery B). Receipt of the complete messageC) In-order delivery D). All of th

8、e above 13The traceroute is implemented with _B_ messagesA) DNS B) ICMPC) ARP D) RIP14Fragments which are smaller IP datagrams need to be reassemble at the _B_A) the destination router B) the destination hostC) the next router D) any router and host15Which routing protocol is the defect of standard

9、inter-AS routing protocol in todays Internet. _D_A) RIP B) OSPFC) IGP D) BGP16The virtual-circuit networks forward packets in their switches use _D_.A) MAC addresses B) IP addressesC) e-mail addresses D) VC numbers 17packet-switching technologies that use virtual circuits include_D_:A) X.25, IP B) X

10、.25, frame relay.C) IPX, IP D) IP, TCP18There are two broad classes of packet-switched networks: datagram networks and virtual-circuit networks. datagram networks forward packets in their switches use _B_.A) MAC addresses B) IP addressesC) e-mail addresses D) virtual-circuit numbers19.if a host want

11、s to emit a datagram to all hosts on the same subnet, then the datagrams destination IP address is _B_A)255.255.255.0 B) 255.255.255.255C)255.255.255.254 D) 127.0.0.120Hub function is in the A layer.A)physical; B) data link; C) Network; D)a and b注：1 试题字迹务必清晰，书写工整。 本题 4 页，本页为第 1 页2 题间不留空，一般应题卷分开 教务处试

12、题编号：3 务必用 A4 纸打印 三、填空题 （每空 1 分，共 20 分 ）1Internet provides both _ connection-oriented and connectionless services to applications 2Internet uses _ packet switching _rather than circuit-switching technology.3Electronic mail including user agents mail servers and SMTP three major components.4. A proces

13、s is identified by ip address as well as port number .5Two important network-layer function can be identified: forwarding , routing .6Network layer services handle data transfer between hosts , transport layer services handle data transfer between processes 7An ARP request is broadcast _ to all host

14、 and an ARP reply is _unicast_ one host;8A link-layer address is variously called a _lan _address, or _physical_address, or _MAC_address.9. Data link layer packet is frame 10Suppose that Host A has established a connection to a process in the server. Please fill in the segments containing data that

15、the client and server hosts can send to each other.四、判断题（每小题 1 分，共 10 分）1The internet applications such as SMTP, HTTP, TELNET us UDP, the internets connectionless-oriented service F2HTTP is mainly a push protocol and SMTP is mainly a pull protocol F3The time required to propagate from the beginning

16、of the link to a router is the propagation delay T4FTP send its control information out-of-band T5link layer address is IP address F6An ARP response sent within a frame with a specific destination MAC address T7An IP address is technically associated with the host or router F8A distance-vector (DV)

17、algorithm computes the least-cost path between a source and destination using complete, global knowledge about the network F9Device s in a subnet can physically reach each other without intervening router T10. In packet-switched networks, a sessions messages use the resources on demand, and Internet

18、 makes its best effort to deliver packets in a timely manner TSource port =1300 Dest port =21Sequence number=1235Acknowledgment number=67905 SYN=0 ACK Receive windowChecksum NIL1000 bytes data Source port =_21_ Dest port =_1300_Sequence number= 6790_ Acknowledgment number= 2235_ 5 SYN=0 ACK Receive

19、windowChecksum NIL1000 bytes data 注：1 试题字迹务必清晰，书写工整。 本题 4 页，本页为第 2 页2 题间不留空，一般应题卷分开 教务处试题编号：3 务必用 A4 纸打印 If Host A Host B Then Host A Host B五、计算题 (30 points)1. consider the following network. With the indicated link costs, use Dijkstras shortest-path algorithm to compute the shortest path from W to

20、all network nodes. 10 分Step N D(x),p(x) D(V),p(v) D(U),p(u) D(y),p(y) D(t),p(t) D(s),p(s)1 W 3,w 1,w 4,w 2 wv 3,w 2,v 4,v 8,v 3 wvu 3,w 4,v 5,u 7,u4 wvux 4,v 5,u 7,u5 wvuxy 5,u 7,u6 wvuxyt 6,t7 wvuxyts最短路径：WX WV WVY WVU WVUT WVUTS 表格 8 分 最短路径 2 分2. Suppose a ISP has been allocated the address block

21、202.12.168.0/24, now if the ISP wants to divide its address block into 6 equal-sized subnet address blocks, and each subnet could include 25 hosts.1) Please utilize CIDRized addresses, determine the length of subnet portion of address.(namely, how many bits should be extend?(2 分 )2) Please write out

22、 the subnet 2#s network prefix(2 分) and subnet mask.(2 分)3) Please write out the subnet 2#s broadcast address.(2 分)4) Please write out the subnet 2#s range of host address.（2 分）答案：1 27 位 prefix 或子网右扩 3 位2 197.23.18.64 , 255.255.255.224 3 197.23.18.954 197.23.18.65-197.23.18.94.注：1 试题字迹务必清晰，书写工整。 本题

23、4 页，本页为第 3 页2 题间不留空，一般应题卷分开 教务处试题编号：3 务必用 A4 纸打印 441334351wx731ustyv3 Consider sending a 3,000-byte datagram into a link that has an MTU of 1500bytes.Suppose the original datagram is stamped with the identification number 422 .Assuming a 20-byte IP header,How many fragments are generated? What are their characteristics?(10 分)Fragment Bytes ID Offset flag1st fragment 1480 (1 分) 422 (0.5 分) 0 (1 分) 1(0.5 分)2st fragment 1480 (1 分) 422 (1 分) 185 (1 分) 1（0.5 分）3st fragment 20 (1 分) 422 (1 分) 370 (1 分) 0(0.5 分)注：1 试题字迹务必清晰，书写工整。 本题 4 页，本页为第 4 页2 题间不留空，一般应题卷分开 教务处试题编号：3 务必用 A4 纸打印