计算机网络与通信期末考试B答案.docx

1、计算机网络与通信期末考试B答案四 川 大 学期 考 试 试 题（B） 闭卷（2008 2009 学年第 2 学期）课程号： 课序号：0 ?7 课程名称：计算机网络与通信 任课教师： 等 成绩：适用专业年级：06 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

2、故认定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. ISP INTERT服务供应商 2. NIC 网络接口卡 3. DNS 域名服务系统 4. MAC介质接入控制 5 BGP边界网关协议 6. MSS最大数据段尺寸 7. FTP 文件传输协议 8 MPLS 多协议标签交换 9 AS自治系统 10. packet switching分组交换二、单项选择题 （每小题l. 5分，共30分) 1We refer to the link-layer packets as D A. messages B. segments C. datagrams D. frames 2

3、The IP protocol lies in C A. application layer B. transport layer C. network layer D. link layer 3 A is a Circuit-switched network. A. TDM B. Datagram network C. Internet D. virtual circuit network 4The packet experiences a B delay as it waits to be transmitted onto the link. A. processing delay B.

4、queuing delay C. propagation delay D. transmission delay5DWhich the following protocols does not use TCP/IP as its underlying protocols?A. SMTP; ; ; 6What is used to specify placement of text, files and objects that are to be transferred from the web server to the client? BA. HTTP D. All of the abov

5、e 7bandwidth is described in _B_ A) Bytes per second B) Bits per second C) megabits per millisecond D) centimeters8) _B_ Is a protocol for transferring a file from one host to another host.A. SMTP; ; ; D. UDP 9In TCP/IP stack, the transport layers flow control mechanism uses B A) slow start B) conge

6、stion avoidance C) three hand-shaking D) sliding window 10Compared with , the new service in is to implement the reliable data transfer over the channel with B A)bit error B) data loss C) data transfer delay D) congestion 11ICMP control messages are transferred in D data unit.A) TCP B).UDP C).ARP D)

7、.IP 12The reliable data delivery between end systems is provided in the C layer of TCP/IP architecture.A) network layer B) data link layer C) transport layer D) session layer 13What is the main function of the network layer? _A_ A. node-to-node delivery; B. process-to-process message delivery C sync

8、hronization; and maintenance of routing tables 14Which IP address is ineffective _D_.A) B) 15If IP address is then subnet prefix is _C_.A) B) C) D) 16The output port of a router dont perform _C_ functions.A) the physical layer functions B) the data link layer functionsC) network management D) buffer

9、 management 17There 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 addresses C) e-mail addresses D) virtual-circuit numbers 18.as show below, which technology isnt

10、typical access networks technongy. C A) digital subscriber line B) hybrid fiber-coaxial cable C) circuit switching D)wireless access 19Which layer-function is mostly implemented in an adapter（NIC）? _A_A) physical layer and link layer B) network layer and transport layerC) physical layer and network

11、layer D) transport layer and application layer 20_A_Which device cant isolate the departmental collision domains. A) Hub; B) switch; C) router; 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 教务处试题编号： 3务必用A4纸打印 三、填空题 （每空1分，共20分?）1_protocols_ define format, order of messages sent and rece

12、ived among network entities, and actions taken on message transmission, receipt. 2The time required to examine the packets header and determine where to direct the packet is part of the _processing_delay.3Any network that forwards packets according to host destination addresses a _datagram_ network.

13、4Within the Internet the most important delays that packet suffered are _processing_ delay, queuing delay, _propagation_ delay, and _transmission_ delay.5Two important network-layer function can be identified: forwarding _ _ , routing _ .6A link-layer address is variously called a _lan_address, or _

14、physical_address, or _MAC_address.7Two generic forms of pipelined reliable date transfer protocols are _ go-Back-N _ and_ selective repeat _810A Web cache also called a _proxy_server_ _.11Suppose a user sitting in a home network behind host 10.0.0.1 requests a Web page on some Web server Please acco

15、rding the NAT translation table at the NAT router. Fill in datagram that include port numbers as well as IP addresses.（有IP缺端口号一个扣分 ）NAT transtation tableWAN sideLAN side 500110.0.0.1, 3345四、判断题（每小题1分，共10分）1The top-down order of the Internet protocol stack is the application, network, transport, link

16、, physical layers (F)2The internets connectionless service makes provision for flow control and congestion control (F)3An ARP response sent within a frame with a specific destination IP address (F)4link layer address is LAN address (T)5Socket is the programming interface between the application laye

17、r and the network layer (F)6Routing involves all of a networks routers (T)7Forwarding table is configured by both Intra and Inter-AS routing algorithm (N)8Any network that forwards packets according to host destination addresses is a VC network (F)9HTTP is mainly a push protocol and SMTP is mainly a

18、 pull protocol (N)10The basic service of link layer is to move a network-layer datagram from one node（router or host）to an adjacent node. (N)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 五、计算题 (30 points)1. consider the following network. With the indicated link costs, use Dij

19、kstras shortest-path algorithm to compute the shortest path from W to all network nodes. 10分 14331534StepND(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,w2wv3,w2,v4,v8,v3wvu3,w4,v5,u7,u4wvux4,v5,u7,u5wvuxy5,u7,u6wvuxyt6,t7wvuxyts最短路径：WX WV WVY WVU WVUT WVUTS2. Suppose, the ISP have

20、been allocated the address block now if the ISP want divide its address block into 6 equal-sized subnet address blocks, and each subnet could include 28 hosts.1) Please utilize CIDRized addresses, determine the length of subnet portion of address.(namely, how many bits should be extend?(2 points )2)

21、 Please write out the subnet 1#s network prefix(2分) and subnet mask.(2分)3) Please write out the subnet 1#s broadcast address.(2分)4) Please write out the subnet 1#s range of host address.（2分）注：1试题字迹务必清晰，书写工整。 本题 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 3. Suppose the generator polynomial is x3+ 1, data bits to be sent D is , what is the CRC bits? Please write the whole compute course. 10分答案：The generator bits G=1001, r=3R = remainderD*2 r /GCRC bits is 011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