计算机网络第二次平时考试教学相关

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1、 计算机网络平时考试试题（带答案） 一、选择题 1．In the Ethernet frame structure, the Data field carries the ( ). A.IP datagram B.segment C.frame D.message 2．The units of data exchanged by a link-layer protocol are called ( ). A. Frames B. Segments C. Datagrams D. bit streams 3．The

2、SYN segment is used for ( ). A.TCP connection setup B.TCP flow control C.TCP congestion control D.Closing a TCP connection 4．The ( ) is a worldwide computer network, that is, a network that interconnects millions of computing devices throughout the world. A. Internet B.

3、Intranet C. switch net D. television net 5．The units of data exchanged by a link-layer protocol are called ( ). A. Frames B. Segments C. Datagrams D. bit streams 6．In Address：,（ ） indicates “host name”. A. www B. uzz C. edu D. cn 7. In the foll

4、owing options, which belongs to the network core? ( ) A. end systems B. routers C. clients D. servers 8．The Internet’s connection-oriented service has a name, it is ( ). A.TCP B. UDP C.TCP/IP D.IP 9．There are two fundamental approaches to building a ne

5、twork core, ( ) and packet switching. A. electrical current switching B. circuit switching C. data switching D. message switching 10．A ( ) protocol is used to move a datagram over an individual link. A. application-layer B. transport-layer C. network-layer D. li

6、nk-layer 11．Services provided by transport layer include ( ). A.HTTP and FTP B.TCP and IP C.TCP and UDP D.ICMP 12．IP addressing assigns an address to 223.10.198.250/29, the network address for this network is ( ). A.223.10.198.248 B. 223.10.198.250 C. 223.10.198.0 D.

7、223.10.0.0 13．IP belongs to ( ).layer? A.transport B.network C.data link D. physical 14．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 card al

8、ways has the same MAC address, no matter where the computer goes. ( ). D. All of the above 15．How many bits specify the IP protocol version in a datagram? ( ). A.1 bit B.2 bits C.4 bits D.8 bits 16．In the following applications, which one is a loss-tolerant applica

9、tion? A E-mail B file transfer C instant messaging D real-time audio 18．The Internet mail system has three components which they are ( ). A.user agent, SMTP, POP3 B.SMTP, POP3, IMAP C.user agent, SMTP, IMAP D.user agent, SMTP, mail server 19．DNS means ( )

10、. A.Data Name System B.Data National System C.Domain Name System D.Domain National System 20．“233.1.1.0/24”, where the /24 notation, sometimes known as a ( ). A. Subnet mask B. Networking address C. Host address D. None of above 21．Which of the following i

11、s not intra-AS routing protocol? ( ) A. RIP B. OSPF C. IGRP D.BGP 22．IP addressing assigns an address to 223.10.198.250/29, the network address for this network is ( ). A. 223.10.198.248 B. 223.10.198.250 C. 223.10.198.0 D. 223.10.0.0 23．IP Data-grams are ra

12、rely larger than ( ). A. 1500 bytes B. 65535 bytes C.500 bytes D.1024 bytes 24．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 card always has the

13、same MAC address, no matter where the computer goes. D. All of the above 25．Which of the following is not belonging to channel partitioning protocols? ( ) A.CSMA B.FDM C.CDMA D. TDM 26. MAC address is ( ) bits long. A.32 B.48 C.128

14、 D.64 27．The Internet’s connection-oriented service has a name, it is ( ). A.TCP B.UDP C.TCP/IP D.IP 28．In the LAN, ( ) protocol dynamically assign IP addresses to hosts. A.DNS B.ARP C.DHCP D.IP 29．Which layer provides host

15、-to-host services? ( ). A. transport B. network C. data link D. physical 30．DHCP protocol is a four-step process: ①DHCP request. ②DHCP ACK. ③DHCP server discovery. ④DHCP server offer(s). The correct sequence is ( ) A.①②③④ B.③②①④ C.③④①② D.①④③② 31．

16、In the Ethernet frame structure, the CRC field is ( ) bytes. A.2 B.4 C.8 D.32 32．Transport-layer protocols run in ( ). A.Servers B.Clients C.Routers D.End system 33．The maximum amount of data that can be grabbed and placed in a segment is limited by the( ). A. Ma

17、ximum segment size (MSS) B. MTU C. Checksum D. Sequence number 34．The internet’s network layer provides a single service----that is ( ). A. Reliable data transfer B. Flow control C. Congestion control D. Best-effort-service 35．There are 6 flag fields. Which one is to indicate that the recei

18、ver should pass the data to the upper layer immediately? ( ) A. PSH B. URG C. ACK D. RST 36．ICMP is used for ( ). A. Reliable data transfer B. Error reporting C. Flow control D.Congestion control 37．The FIN segment is used for ( ). A. TCP connectio

19、n setup B. TCP flow control C. TCP congestion control D. Closing a TCP connection 38．A transport-layer protocol provides for logical communication between ( ). A. Application processes B. Hosts C. Routers D. End systems 39．Port number’s scope is ( ) to

20、 ( ). A. 0, 1023 B. 0, 65535 C. 0, 127 D. 0,255 40．“233.1.1.0/24”, where the /24 notation, sometimes known as a( ). A. Subnet mask B. Networking address C. Host address D. None of above 二、判断题 1．In CSMA/CD, one node listens to the channel before transmitting. T 2．In C/S ar

21、chitecture, client has a fixed well-known address. F 3．In P2P architecture, peers communicate with each other directly. T 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 response.F 6．In full-duplex transmissio

22、n(s), the nodes at both ends of a link may transmit packets at the same time. T 7．DNS resolves hostnames for hosts anywhere in the Internet. T 8．ARP resolves an IP address to a MAC address. T 9．In the broadcast packet of DHCP DISCOVER，source IP address is 0.0.0.0. T 10．The routing algorithm runn

23、ing within an autonomous system is called an intra-AS routing protocol. F 11．In CSMA/CD, one node listens to the channel before transmitting. T T 12．All of the Ethernet technologies provide connection-oriented reliable service to the network layer. F 13．A router receives a packet, in which TTL=

24、0, and the packet will be dropped. T 14. Datagram networks are circuit-switched networks, and virtual-circuit networks are packet-switched networks. F 15．ARP resolves an IP address to a MAC address. T 16．If the traffic intensity is close to zero, the average queuing delay will be close to zero. T

25、 17．A router receives a packet, in which TTL=0, and the packet will be dropped. T 18．The adapter is also called as NIC. T 19．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 010. F 20．Hubs can interconnect dif

26、ferent LAN technologies. F 三、填空题 1. Common Channel multiplexing technology includes _FDM_、_TDM_、_WDM_、__CDM__. 2．NIC works in _data link_ layer of Internet. 3. __network_ layer provides host-to-host services, and _transport_ layer provides process-to-process services. 4．MAC address is _48_ bits

27、, and IPV4 has a 32_ bit address. 5．The data transmission delay include: _propagation delay_、__transmission delay_、processing delay and queuing 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

28、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，LAN2~LAN5的主机数为：93，147，23，20。

29、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10110011010，生成多项式为G（x）＝x4＋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） （1）本次应用基于应用层的______协议，基于传输层的_______协议。 （2）上图中，数据包133是一个______数据包，134是一个______数据包，135是一个_______数据包。（A. 连接接受

30、 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________的数据包（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。 212.56.132.0/24，212.

31、56.133.0/24，212.56.134.0/24，212.56.135.0/24。（8分） 5．现有五个站分别连接在三个局域网上，并且用两个透明网桥连接起来，如下图所示。每一个网桥的两个端口号都标明在图上。在一开始，两个网桥中的转发表都是空的。以后有以下各站向其他的站发送了数据帧，即H1发送给H5，H3发送给H2，H4发送给H3，H2发送给H1。 试将有关数据填写在下表中。（9分） 发送的帧 网桥1的转发表 网桥2的转发表 网桥1的处理 （转发？丢弃？登记？） 网桥2的处理 （转发？丢弃？登记？） 站地址 端口 站地址 端口 H1H5

32、 H3H2 H4H3 6．设某路由器建立了如下所示的转发表： 目的网络 子网掩码 下一跳 128.96.39.0 255.255.255.128 接口0 128.96.39.128 255.255.255.128 接口1 128.96.40.0 255.255.255.128 R2 192.4.153.0 255.255.255.192 R3 *（默认） R4 此路由器可以直接从接口0和接口1转发分组，也可通过相邻的路由器R2，R3和R4 进行转发。现共收到4个分组，其目的站IP地址分别为

33、 （1）128.96.39.10，（2）128.96.40.12，（3）128.96.40.151，（4）192.4.153.17试分别计算其下一跳。（8分） 7．设TCP使用的最大窗口为65535字节，而传输信道不产生差错，带宽也不受限制。若报文段的平均往返时延为20ms，问所能得到的最大吞吐量是多少?（5分） 8．主机A向主机B连续发送了两个TCP报文段，其序号分别为70和100。试问： （1）第一个报文段携带了多少个字节的数据？ （2）主机B收到第一个报文段后发回的确认中的确认号应当是多少？ （3）如果主机B收到第二个报文段后发回的确认中的确认号是180，试问A发送的第二个报文段中的数据有多少字节？ （4）如果A发送的第一个报文段丢失了，但第二个报文段到达了B。B在第二个报文段到达后向A发送确认。试问这个确认号应为多少？（共8分） 9．假定1km长的CSMA/CD网络的数据率为1Gb/s。设信号在网络上的传播速率为200000km/s。求能够使用此协议的最短帧长。（5分） 10．一个IP数据报长度为3980字节（固定首部长度）。现在经过一个网络传送，但此网络 能够传送的最大数据长度为1500字节。试问应当划分为几个短些的数据报片？各数据 报片的数据长度、片偏移字段和MF标志应为何值？（8分） 6 试题和教育