计算机网络-第二次平时考试

1、精品文档计算机网络平时考试试题 （带答案）一、选择题1. In the Ether net frame structure, the Data field carries the ().A. IP datagramB.segme ntC.frameD.message2. The units of data exchanged by a link-layer protocol are called ().A. FramesB. Segme ntsC. Datagrams D. bit streams3. The SYN segment is used for ().A.TCP conn ecti

2、on setupB.TCP flow con trolC.TCP con gesti on con trolD.Closi ng a TCP connection4. The ( ) is a worldwide computer network, that is, a network that interconnects millions of comput ing devices throughout the world.A. InternetB. IntranetC. switch net D. televisi on net5. The units of data exchanged

3、by a link-layer protocol are called ().A. FramesB. Segme ntsC. DatagramsD. bit streams6. In Address： , () indicates host namd'.A. wwwB. uzzC. eduD. cn7. In the following options, which belongs to the network core?()A. end systems B. routersC. clie ntsD. servers8. The Internet'connection-orie

4、nted service has a name, it is ().A.TCPB. UDPC.TCP/IPD.IP9. There are two fun dame ntal approaches to build ing a n etwork core, ( ) and packet switchi ng.A. electrical curre nt switch ingB. circuit switchi ngC. data switchi ngD. message switchi ng10. A () protocol is used to move a datagram over an

5、 in dividual li nk.A. applicati on-layerB. tran sport-layerC. n etwork-layerD. li nk-layer11. Services provided by transport layer include ().A.HTTP and FTP B.TCP and IP C.TCP and UDP D.I CMP12. IP addressing assigns an address to 50/29, the network address for this network is ().A.223.1

6、0.198.248 B. 50C. D. 13. IP belongs to ( ).layer?A.tra nsportB.n etworkC.data linkD. physical14. Which of the following is correct?()A. No two adapters have the same MAC address.B. MAC broadcast address is FF-FF-FF-FF-FF-FF.C. A portable computer with an Ethernet c

7、ard always has the same MAC address, no matter where the computer goes.().D. All of the above15. How many bits specify the IP protocol version in a datagram?().A.1 bitB.2 bitsC.4bitsD.8 bits16. In the following applications, which one is a loss-tolerant application?A E-mailB file tran sferCin sta nt

8、 messagi ngD real-timeaudio18. The Internet mail system has three components which they are ().A.user agent, SMTP, POP3B.SMTP, POP3, IMAPC.user age nt, SMTP, IMAPD.user age nt, SMTP, mail server19. DNS means ().A.Data Name SystemB.Data Natio nal SystemC.Doma in Name SystemD.Doma in Nati onal System2

9、0. “/24 where the /24 notation, sometimes known as a ().A. Subnet maskB. Network ing address C. Host address D. None of above21. Which of the following is not intra-AS routing protocol?()A. RIPB. OSPFC. IGRPD.BGP22. IP addressing assigns an address to 50/29, the network address

10、for this network is ().A. 48 B. 50C. D. 23. IP Data-grams are rarely larger than ().A. 1500 bytes B. 65535 bytesC.500 bytesD.1024 bytes24. Which of the following is correct?()A. No two adapters have the same MAC address.B. MAC broadcast address is FF-FF

11、-FF-FF-FF-FF.C. A portable computer with an Ethernet card always has the same MAC address, no matter where the computer goes.D. All of the above25. Which of the following is not belonging to channel partitioning protocols?()A.CSMAB.FDMC.CDMAD. TDM26. MAC address is ( ) bits long.A.32B.48C.128D.6427.

12、 The In ternet'co nn ectio n-orie nted service has a n ame, it is ().A.TCPB.UDPC.TCP/IPD.IP28. In the LAN, () protocol dynamically assign IP addresses to hosts.A.DNSB.ARPC.DHCPD.IP29. Which layer provides host-to-host services?().A. tran sportB. n etworkC. data linkD. physical30. DHCP protocol i

13、s a four-step process: DHCP request.DHCP ACK.DHCP server discovery. DHCP server offer(s). The correct seque nee is ()A.B.C.D.31. In the Ethernet frame structure, the CRC field is ( ) bytes.A.2B.4C.8D.3232. Tran sport-layer protocols run in ().A.ServersB.Clie ntsC.RoutersD.E nd system33. The maximum

14、amount of data that can be grabbed and placed in a segment is limited by the(.A. Maximum segme nt size (MSS) B. MTU C. Checksum D. Seque nee number34. The in ternet ' s n etwork layer provides a si ngle servicai is ( ).A. Reliable data tran sfer B. Flow con trol C. Con gesti on con trolD.Best-ef

15、fort-service35. There are 6 flag fields. Which one is to indicate that the receiver should pass the data to the upper layer immediately?()A. PSHB. URGC. ACKD. RST36. ICMP is used for ().A. Reliable data tran sferB. Error report ingC. Flow con trolD.C on gestio n con trol37. The FIN segment is used f

16、or ().A. TCP co nn ection setupB. TCP flow con trolC. TCP con gesti on con trolD. Closi ng a TCP connection38. A tran sport-layer protocol provides for logical com muni cati on betwee n ().A. Applicati on processesB. HostsC. Routers D. End systems39. Port number ' s scope i9 to ().A. 0,1023B. 0,

17、 65535C. 0,127D. 0,25540. “ /24” , where the /24 notation, sometimes knoWn )as aA. Subnet mask B. Network ing address C. Host address D. None of above二、判断题1. In CSMA/CD, one node listens to the channel before transmittingT2. In C/S architecture, client has a fixed well-known addressF3. In P

18、2P architecture, peers com muni cate with each other directly.4. Each TCP connection is closed after the server sending one object.5. There are four steps in DHCP, the DHCP server can complete DHCP responFe.6. In full-duplex tran smissi on( s), the no des at both ends of a link may tran smit packets

19、 at the same time. T7. DNS resolves host names for hosts any where in the In terneT8. ARP resolves an IP address to a MAC addresT9. In the broadcast packet of DHCP DISCOVER source IP address is T10. The routing algorithm running within an autonomous system is called an intra-AS routing protoc

20、ol. F11. In CSMA/CD, one node listens to the channel before transmittingTT12. All of the Ether net tech no logies provide connection-orie nted reliable service to the n etwork layer. F13. A router receives a packet, in which TTL=0, and the packet will be droppedT14. Datagram networks are circuit-swi

21、tched networks, and virtual-circuit networks are packet-switched n etworks.F15. ARP resolves an IP address to a MAC address.16. If the traffic in ten sity is close to zero, the average queu ing delay will be close to zercT17. A router receives a packet, in which TTL=0, and the packet will be dropped

22、T18. The adapter is also called as NICT19. Consider CRC error checking approach, the four bit generator G is 1011, and suppose that the data D is 10101010, then the value of R is 010F20. Hubs can in terc onnect differe nt LAN tech no logies.F三、填空题1. Com mon Cha nnel multiplexi ng tech nology in clud

23、es _FDM_、_TDM_、_WDM_、_CDM_.2. NIC works in _data link_ layer of In ternet.3. _network_ layer provides host-to-host services, and _transport_ layer providesprocess-to-process services.4. MAC address is _48_ bits, and IPV4 has a32_ bit address.5. The data transmission delay include: _propagation delay

24、_、_ransmission delay_、processingdelay and queu ing delay.6. The port number used by HTTP is _80_; The port number used by SMTP is _25_; The port number used by DNS is _53_.7. 在TCP连接建立过程中，客户端向服务器发送一个连接请求的TCP报文，其中包含连接 的初始序列号v和一个窗口大小，服务器收到报文后，向客户端发送一个请求确认的报文，其中包含它选择的初始序列号 w.确认号为_V+1_，和一个窗口大小。四.简答题1. 比较

25、TCP协议和UDP协议之间的异同点。2. 比较分组交换和电路交换之间的优缺点。3简述HTTP代理服务器的作用。4. 数据链路层的三个基本问题是什么？简单论述一下。5. 简述两种DNS服务器查询方式。6. 简单论述CSMA/CD的工作原理。7. 简述TCP的三次握手协议。五、应用题1. 一个自治系统有5个局域网，其连接图如图所示，LAN2LAN5的主机数为：93，147,23, 20。该自治系统分配到的IP地址快为199.138.118/23试给出每一个局域网的地址块 （包 括前缀）。（10分）2. 数据传输过程中，若接收方收到发送方送来的信息为1011001101Q生成多项式为G （x）=x4

26、 + x3+ 1,接收方收到的数据是否是正确的？（请写出判断依据及推演过程）（5分）3. 用Ethereal工具捕获到如下数据包，请根据图的内容回答如下问题。（8 分）133 14,326242222.194222.154.139,2-iTCP> frp 鼻5Q=C14.32656?44222.1W.14L.2-BTCPrtp > 2274 |5Yi, AC<1 seq=Q Aclc< bi 1 rlt364 LerH) M55=14135 M.32661B136 li.320061137 li.4-iO3E145 15.S653G7146 1

27、5.85507514S 16.Q53i?4222ASJ.l-l.2if222AU1R24441 22L194.141.2 22.134ZU22L194.14L24822L194.139J44 222.1W.141J-8 22Z1W. 139.244 222.194.13». 24 222,W.139.24iTCP F'P TCPFTP FTP KP221 > ftp 建K ieq-L 4ck-L ftir-555 TcmECKSuP IK Response: 220 Ser.-II FTP Server ;6.4 fo

28、r tfinSock ready. 22-1 > ftp -CKAck-iO «iin-£54Sfi tcp CHLCKSkM ARequest: user v.hResponse: 331 user naae oka;, need password.】厂1 > ftoHf 53-lj Atk-se 'rt'n-65-SC (TCF CHECKS':百 旷却电1弭(56 Eyt出an tir名 朋bytM lap二u凶)二 Ethernet ir, src： 7yancopLCB：(il:De险：50：af ：73:12：bdic7 (5

29、0:af :73:12:lxl:c7)E imerret Protocol, Src： 222,IM,139.244 (222,194,139,244), DSC： 48 (222,194.141.248)三 ifnsirisslon control Protocol, src Port： ftp (21, ost port： 2274 (2274), s&q: 0, it Len： 0Sotrce pore; ftp 21) oesrinakion port; 2274 (2274)iecuence rjrter: 0aliverunber)A&iw

30、dedgeirein rwbe; 1 relirfve ack rwber)Headsr length: 12 bytesa Flags: OxC-312 5Yk1 ACK) wirdc.-J size： 15?i4checksur： Oxblfb correct3 options: 12 bytes)（1） 本次应用基于应用层的 、议，基于传输层的 、议。（2）上图中，数据包133是一个 据包，134是一个 据包，135是一个数据包。（A.连接接受 B.连接确认 C.连接请求）（3） 查看Packet Detail窗口信息，可以看出：133数据包的源端口号为 ，目的端口号为 表示这是一个从 到勺数据包（填写 Client或者 Server）。（4） 此数据包的传输层首部长度为 字节，其中固定首部长度为 字节，标识字段都有 URG、ACK、PSH、RST、SYN、共六种，其中数据包 136的控制字段应为=1 &&=1。4. 有如下的四个/24地址块，试进行最大可能的聚合。/24, /24, /24, /24 （8 分）5. 现有五个站分别连接在三个局