计算机网络与通信期末考试b答案Word下载.docx

1、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

2、 the link-layer packets as D A. messages B. segments C. datagrams D. frames 2The 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

3、 B delay as it waits to be transmitted onto the link. A. processing delay B. queuing delay C. propagation delay D. transmission delay5DWhich the following protocols does not use TCP/IP as its underlying protocols?A. SMTP; B.FTP; C.TELNET; D.TFTP6What is used to specify placement of text, files and o

4、bjects that are to be transferred from the web server to the client? BA. HTTP B.HTML C.HDLC D. All of the above 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.

5、C.TCP; D. UDP 9In TCP/IP stack, the transport layers flow control mechanism uses B A） slow start B） congestion avoidance C） three hand-shaking D） sliding window 10Compared with rdt2.0, the new service in rdt3.0 is to implement the reliable data transfer over the channel with B A）bit error B） data lo

6、ss C） data transfer delay D） congestion 11ICMP control messages are transferred in D data unit.A） TCP B）.UDP C）.ARP D）.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

7、is the main function of the network layer? _A_ A. node-to-node delivery; B. process-to-process message delivery C synchronization; D.updating and maintenance of routing tables 14Which IP address is ineffective _D_.A） 202.131.45.61 B） 127.0.0.1C） 192.168.0.2 15If IP address is 198.108.126.66224, then

8、 subnet prefix is _C_.A） 198.108.126.60 B） 198.108.126.0 C） 198.108.126.64 D） 198.108.126.224 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 management 17There are two broad classes of packet-sw

9、itched 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 typical access networks technongy. C A） digital subscr

10、iber 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 layer D） transport layer and application layer 20_A_Wh

11、ich 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 received among network entities, and actions taken on mess

12、age 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.4Within the Internet the most important delays that pa

13、cket 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 _physical_address, or _MAC_address.7Two generic forms o

14、f 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 according the NAT translation table at the NAT router. Fil

15、l in datagram that include port numbers as well as IP addresses.（有IP缺端口号一个扣0.5分 ）NAT transtation tableWAN sideLAN side138.76.29.7, 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, physical layers （F）2The internets con

16、nectionless 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 layer and the network layer （F）6Routing inv

17、olves 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 pull protocol （N）10The basic service o

18、f link layer is to move a network-layer datagram from one node（router or host）to an adjacent node. （N） 本题 4 页，本页为第 2 页 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 Dijkstras shortest-path algorithm to compute the shortest path from W to all network

19、 nodes. 10分 1435StepND（x）,p（x）D（V）,p（v）D（U）,p（u）D（y）,p（y）D（t）,p（t）D（s）,p（s）W3,w1,w4,w2wv2,v4,v8,vwvu5,u7,uwvuxwvuxy6wvuxyt6,t7wvuxyts最短路径：WX WV WVY WVU WVUT WVUTS2. Suppose, the ISP have been allocated the address block 197.23.18.0/24, now if the ISP want divide its address block into 6 equal-sized

20、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） Please write out the subnet 1#s network prefix（2分） and subnet mask.（2分）3） Please write out the s

21、ubnet 1#s broadcast address.（2分）4） Please write out the subnet 1#s range of host address.（2分） 本题 4 页，本页为第 3 页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 本题 4 页，本页为第 4 页