2006-2007第一學(xué)期計(jì)算機(jī)網(wǎng)絡(luò)試卷1A

1、天津理工大學(xué)考試試卷 2006 2007 學(xué)年度第 1 學(xué)期計(jì)算機(jī)網(wǎng)絡(luò)技術(shù) 期末考試試卷課程代碼： 試卷編號(hào)： 1-A 命題日期： 2006 年 12 月 10 日答題時(shí)限： 120 分鐘 考試形式：閉卷筆試得分統(tǒng)計(jì)表：大題號(hào)總分 一二三四五PART : Choice (1 point per question total: 20 points)Instructions: Select one of the letters beside the choice that is the best answer for each question. 得分Q1234567891011121314151

2、617181920A1. End system are connected together by _. A. communication links B. application layer C. transport layer D. the network layer2. Which applications NOT using TCP? A. SMTP B. HTTPC. DNS D. All of them3. In the polling protocols, the master node polls each of the nodes in a/an _ fashion. A.

3、random B. appointed C. round-robin D. uncirculated 4. The DNS protocol runs over _ and uses port _. A. UDP 36 B. TCP 36 C. UDP 53D. TCP 535. TCP provides a _ service to its applications to eliminate the possibility of the sender over-flowing the receivers buffer. A. flow-controlB. congestion control

4、C. reliability controlD. data connection6. We can classify just about any multiple access protocol as belonging to one of three categories: channel partitioning protocols, random access protocols, and _. A. address resolution protocols B. Dynamic host configuration protocols C. link-control protocol

5、s D. taking-turns protocols 7. The job of delivering the data in transport-layer segment to the correct socket is called_. A. multiplexing B. demultiplexing C. congestion controlD. data-transport8. The maximum transfer unit(MTU) in Ethernet frame structure is _byte .A. 1000 B. 1500 C. 800 D. 2000 9.

6、 The socket of UDP is identified by _ and _. A. source IP address and source port number B. destination IP address and destination port number. C. source IP address and destination port number. D. destination IP address and source IP address.10. Which is not plug and play in the following four items

7、? A. DHCP B. Hubs C. Routers D. Switches 11Which of routers is not default routers ? A. first-hop router B. source router C. destination router D. second-hop router 12Which of characters is not distance-vector algorithms characters？ A. iterativeB. globalC. asynchronousD. distributed13. ICMP is_. A.

8、the protocol of Application layer B. the protocol of network layerC. the protocol of transport layer D. not a part of TCP/IP protocols 14. As general, we has following channel partitioning protocols except _. A. TDM B. CSMA C. FDM D.CDMA15. _ is most used for error reporting. A. UDP B. SMTP C. FTP D

9、. ICMP16. The header of IPV6 is _byte. A. 20 B. 40C. 60D. 8017. In the network layer these service are host-to-host service provided by _. A. the transport layer to the network layerB. the network layer to the transport layerC. the network layer to the network layerD. the transport layer to the tran

10、sport layer18. If there is not enough memory to buffer an in coming packet , a policy that drop the arriving packet called _. )A. drop-tailB. packet lossC. protocolD. encapsulation19. In either case, a _ receives routing protocol messages, which are used to configure its forwarding table. A. server

11、B. host C. router D. Modem20. Which of the following functions does not belong to PPP_. A. framingB. link-control protocols C. network-control protocols D. error correctionPART : True / False (1 points per question total:20 points) Instructions: Mark the symbol “” (for True) if the statement is corr

12、ect, or the symbol “X” (for False) if the statement is incorrect.得分Q1234567891011121314151617181920A1. The DNS server can update the records. 2. The TCP connection is a direct virtual pipe between the clients socket and the servers connection socket. 3. SMTP protocol connect the senders mail server

13、and receivers mail server 4. Whereas a transport-layer protocol provides logical communication between processes running on different hosts, a network-layer protocol provides logical communication between hosts. 5. UDP and TCP also provide integrity checking by including right-detection fields in th

14、eir headers. 6. If the application developer chooses UDP instead of TCP, then the application is not directly talking with IP. 7. When we develop a new application, we must assign the application a port number. 8. Real-tine applications, like Internet phone and video conferencing, react very poorly

15、to TCPs congestion control. 9. The sender knows that a received ACK or NAK packet was generated in response to its most recently transmitted data packet. 10. To simplify terminology, when in an Internet context, we refer to the 4-PDU as a unit. 11. DV algorithm is essentially the only routing algori

16、thm used in practice today in the Internet。12. Every router has many forwarding tables. 13.In either case, a server receives routing protocol messages,which are used to configure its forwarding table. 14. Among the ASs, they run the same inter_AS routing protocol. 15. Routing protocols job is to det

17、ermine the path take by a datagram between source and destination. 16. OSPF was one of the earliest intra_AS Internet routing protocols. 17. The IPV6 datagrams are more simpler, more streamlined. 18. Forwarding tables in datagram networks can be modified at any time.19. In a VC network, the networks

18、 routers must maintain connection state information for the ongoing connections.20. The routers of datagram networks use forwarding table, the routers of virtual-circuit networks dont use forwarding table.PART : Fill in the following blank with a or some appropriate word/words. (1 points per blank t

19、otal: 20 points)得分1. In the “10BaseT”,T stands for ( ). 2. ( ) and ( ) are two of the most important protocols in the internet. 3. In a client-server architecture, there is an always-on host , called the ( ), which services requests from many other hosts, called ( ). 4. The broadcast destination IP

20、address is ( ). 5. Two of the more important ( ) protocols are polling protocols and token-passing protocol. 6. Transport-layer protocols are implemented in the ( ), but not in network router. 7. The port numbers ranging ( ) are called well-known port numbers. 8.The ( ) algorithm is used in many rou

21、ting protocols in practices, including the Internets RIP and BGP, Novell IPX, and the original ARPAnet. 9. Internet consists of hierarchy of interconnected ( ). 10. In MAC address, broadcast address is ( ). 11. AS is a collection of( ) under the same administrative and technical control. 12. ( ) and

22、 FDM are two techniques that can be used to partition a broadcast channels bandwidth among all nodes sharing that channel. 13. As the queues grow large, the routers buffer space will eventually be exhausted and ( ) packet loss will occur. 14. The role of the network layer is to move ( ) from a sendi

23、ng host to a receiving host. 15. ( ) refers to the router-local action of transferring a packet from an input link interface to the appropriate output link interface. 16.The Internets network layer provides asingle service,known as ( ).17. The units of data exchanged by a link-layer protocol are cal

24、led ( ). 18. The ( ) -layer protocol defines the format of the packets exchanged between the nodes at the ends of the link, as well as the actions taken by these nodes when the packets are sent and received. Answer: 20 blanksPART : Briefly Compare and contrast the each pair items below. Each answer

25、of items pair should be at least 2 paragraphs. (4 points per question total: 8 points)得分1(4points) Connection-Oriented/Connectionless2(4points) UDP/TCPPART : Answer each of the following questions. (Total: 30 points)得分1. (5 points) The diagram below depicts the 5-layer TCP/IP model weve used in clas

26、s. Put the name of each layer inside each box.2. (5 points)Using the layers from the above diagram, label each technology item below with the best associated layer it fits into (use the layer number from above) (1 point for each): User Datagram Protocol (UDP) Medium Access Control (MAC) HTTP (web br

27、owser) Copper cabling (e.g. Category 5 specification) Internet Protocol (IP) Transparent bridging Distance vector routing algorithms (e.g. RIP) Transmission signal attenuation Chatting with friends(QQ) Transmission Control Protocol (TCP)3. (total: 8 points) Reno congestion control algorithm.Consider

28、 TCP Reno (the one that uses both timeout and 3 duplicate ACKs to detect packet losses). Remember the receiver sends cumulative ACK whenever a segment is received and assume that our TCP implementation discards out-of-order segments, so as in Go-Back-N, the sender should re-transmit all packets star

29、ting from base when a packet loss is detected. Remember congestion window needs to be adjusted before retransmission.A server application has 26 TCP segments (packets) (that are numbered as 1, 2, 3 26) to send to the receiver site. Assume that the sender started from slow start with a congestion win

30、dow of 1 and continued according to TCP Reno congestion control algorithm. The initial Threshold value was 4. The timeout duration at the sender is set to RTT. Assume that the sender sends a number of TCP segments and receives all ACKs just before the next RTT (ignore the time between back-to-back s

31、ent segments). Finally, assume that 15th and 21st segments got lost during their first transmission.Now, by using the above information, your task is to complete the blank entries in the below table until all the segments are sent and all the ACKs are successfully received. If you want, you can use

32、the chart below to work out your solution before filling in the table below.Cong. Win. CHART987654321 0 1 2 3 4 5 6 7 8 9 10 11 RTT RTTThresholdCongestion WindowSegments that are sent04111422, 32345678910TABLE3.（6 points）Consider the following network N running a distance vector protocol. We are onl

33、y interested in the shortest routes to the node S. C 8 1 20 2 S A B(1) Assume that the cost of the edge AB increases to 20. Show how the routing information changes at nodes B and C if poisoned reverse is not used. （4 points）Initially B thinks shortest path (SP) is of length 22 via A and C thinks sh

34、ortest path is of length 23 via B.After the change the following sequence of events happen:B updates SP to 24 via CC updates SP to 25 via BB updates SP to 26 via CC updates SP to 27 via BB updates SP to 28 via CC updates SP to 28 via AB updates SP to 29 via C(2) Assume that the cost of the edge AB i

35、ncreases to 20. Show how the routing information changes at nodes B and C if poisoned reverse is used. （2 points）Initially B thinks shortest path (SP) is of length 22 via A and C thinks shortest path is of length 23 via B.After the change the following sequence of events happen:B updates SP to 40 via AC updates SP to 28 via AB updates SP to