Computer network technology final exam mock test questions and answers
1. Fill in the blanks (0.5 points per question, 10 points in total)
1. In systems that use electrical signals to express data, there are two types of data: digital data and analog data .
2. Domain Name System DNS is a distributed database system.
3. The most important protocol in the network layer of TCP/IP is the IP Internet Protocol , which can connect multiple networks into an Internet.
4. The protocols included in the network layer of the TCP/IP hierarchical model mainly include ARP , RARP, ICMP, and IP .
5. The campus network widely adopts client/server , and its resource distribution generally adopts hierarchical
6 There are two types of transport services in the transport layer: connection - oriented and connectionless services .
7. The three basic services provided by the Internet are E-mail. Telnet. FTP .
8. In the IEEE802 local area network architecture, the data link layer is subdivided into two layers: LLC logical link sublayer and MAC media access control sublayer .
10. IEEE802.3规定了一个数据帧的长度为64字节到1518字节之间。
12. 信道复用技术有.时分多路复用，频分多路复用，波分多路复用。
二. 单选（每题1分，共30分）
1. 世界上第一个计算机网络是 （A）。
A. ARPANET B. ChinaNet C.Internet D.CERNET
2. 计算机互联的主要目的是（D）。
A. 制定网络协议 B. 将计算机技术与通信技术相结合 C. 集中计算 D.资源共享
4. 下列不属于路由选择协议的是（B）。
A. RIP B. ICMP C. BGP D. OSPF
5. TCP/IP参考模型中的主机-网络层对应于OSI中的（D）。
A.网络层 B、.物理层 C.数据链路层 D.物理层与数据链路层
6. 企业Intranet要与Internet互联，必需的互联设备是（D）。
A. 中继器 B. 调制解调器 C. 交换器 D. 路由器
7. 通信系统必须具备的三个基本要素是（C）。
A. 终端. 电缆. 计算机 B. 信号发生器. 通信线路. 信号接收设备
C. 信源. 通信媒体. 信宿 D. 终端. 通信设施. 接收设备
9. Below (D) is not one of the scopes of the group.
A. Universal scope B. Global scope C. Local scope D. Domain-local scope
10. A station in a token ring network can send frames because of (C).
A. The first to apply B. The highest priority C. The token arrives D. Can be sent randomly
11. Local area communication network is referred to as local area network , and its English abbreviation is (B).
A. WAN B. LAN C. SAN D.MAN
12. When a computer downloads a file from an FTP server, the five transformation steps to encapsulate the data on the FTP server are (B).
A. bit, data frame, data packet, data segment, data B. data , data segment, data packet, data frame, bit
C. Packet, Segment, Data, Bit, Frame D. Segment, Packet, Frame, Bit, Data
13. In the TCP/IP protocol suite, the UDP protocol works in (B).
A. Application layer B. Transport layer C. Network interconnection layer D. Network interface layer
14. A company has applied for a Class C network. Due to geographical considerations, it must be divided into 5 subnets. Please set the subnet mask to (A) 11100000 host ID
A. 255.255.255.224 B. 255.255.255.192
C. 255.255.255.254 D. 255.285.255.240
15. In the following protocol, (B) is used for email transmission control .
A. SNMP B. SMTP C. HTTP D.HTML
16. At the same time on the same channel, the communication method capable of bidirectional data transmission is (C).
A. Simplex B. Half-duplex C. Full-duplex D. None of the above three
17. The basis for mutual communication between various networks and different types of computers on the Internet is (A).
A. HTTP B. IPX/SPX C. X.25 D. TCP/IP
18. The mechanism of Ethernet media access control technology CSMA/CD is (A).
A. Competing for bandwidth B. Reserving bandwidth C. Reusing bandwidth D. Allocating bandwidth according to priority
19. In OSI, in order to achieve effective and reliable data transmission, the transmission operation must be strictly controlled and managed, and the level to complete this work is (B).
A. Physical layer B. Data link layer C. Network layer D. Transport layer
21. A frame relay network is a (A).
A. Wide area network B. Local area network C. ATM network D. Ethernet
22. Which of the following statements about user accounts is correct (B).
A．A user account is a computer account B. A user account is identified by a username and password
C．User accounts are at the same level as group accounts D. User accounts are created when Windows 2000 Server is installed
23. www.tsinghua.edu.cn in this full name (FQDN), (D) is the host name
A. edu.cn B. tsinghua C. tsinghua.edu.cn D. www
24. The default TCP port number for FTP service below is (A).
A. 21 B. 25 C. 23 D. 80
27. The name provided by Windows 2000 Server for administrators is (C).
A．Guest B．TsInternetUser C．Administrator D．Domain Admins
28. The first message sent by the DHCP client when applying for an IP address lease is the following (D).
A. DHCP discover Ｂ. DHCP offer C. DHCP request Ｄ. DHCP positive
29. Computer network communication adopts both synchronous and asynchronous methods , but the one with the highest transmission efficiency is (A).
A．Synchronization method B．Asynchronous mode c. Synchronous and asynchronous transmission efficiency is the same D. Can not be compared
30. In the Internet domain name system, sub-domains can be divided under the domain , and the domain names at all levels are separated by dots, according to (D).
A. Arrange in 4 layers in a way of getting smaller and smaller from left to right B. Arrange in multiple layers in a way of getting smaller and smaller from left to right
C. Arranged in 4 layers in a way that gets smaller and smaller from right to left D. Arranged in multiple layers in a way that gets smaller and smaller from right to left
3. Explanation of terms (4 points for each question, 20 points in total)
1. Computer network: A computer network is "a collection of autonomous computer systems interconnected by sharing resources with each other".
2. TCP/IP protocol: It was developed by DARPA, the Advanced Research Projects Agency of the US Department of Defense, to realize the ARPANET Internet. TCP/IP has become a de facto industry standard. TCP/IP is synonymous with a group of protocols, and it also includes many other protocols, forming the TCP/IP protocol cluster. TCP provides transport layer services, while IP provides network layer services. As a network architecture, the TCP/IP protocol is divided into four layers, which are host-network layer, Internet layer, transport layer and application layer from bottom to top.
3. Multiplexing : In data communication or computer network systems, the bandwidth or capacity of transmission media often exceeds the requirements for transmitting a single signal. In order to effectively use communication lines, one channel can be used to transmit multiple signals. This method is called For the multiplexing of channels, referred to as multiplexing.
4. DHCP : Dynamic Host Configuration Protocol (DHCP) is a LAN network protocol , using UDP protocol to work, mainly for two purposes : to automatically assign IP addresses to internal networks ornetwork service providers, to users or internal network administrators asA means of centrally managingall computers
4. Short answer (5 points for each question, 20 points in total)
1. What is a local area network? What are the characteristics?
LAN is a computerized communication network that supports device interconnection, information exchange and resource sharing among various data communication devices. The main features are: (1) The geographical coverage is small, and all sites share a high total bandwidth (that is, a high data transmission rate (generally greater than 10Mbps, up to 1Gbps); (2) Has a small delay and relatively Low bit error rate: (3) An equal relationship rather than a master-slave relationship is formed between each site. (4) Broadcast or multicast (also known as multicast) can be performed.
2. Organizations that can provide the best network equipment usually choose switches over hubs. Why?
Because the switch itself has the advantages of overall speed (the switch is much faster), smarter routing method or electronic logic, higher port count, etc.
3. What are the characteristics of connection-oriented and connectionless services .
For connection-oriented services, the two communicating parties must establish a complete communication channel between the two parties before communicating. During the communication process, the entire connection can be monitored and managed in real time. Instead of a connection service, there is no need to establish a connection between two communication nodes in advance. When communication is required, the sending node can send information to the "network", allowing the information to be transmitted on the network autonomously. The process is no longer monitored.
4. What is the working process of DHCP ?
1. Find a dhcp server 2. The server provides an IP leased address
3. Host A accepts the IP lease 4. Lease confirmation:
5. Comprehensive application (10 points for each question, 20 points in total)
1. Briefly describe the preparations required to connect to the Internet using "dial-up networking".
(1) Select a suitable ISP and obtain an Internet account through the ISP;
(2) Prepare a modem and a telephone line that can dial the ISP;
(3) Install "Dial-Up Networking";
(4) Install the TCP/IP protocol and bind it to the "dial-up network adapter";
(5) Input TCP/IP related information;
(6) Use "dial-up networking" to establish a connection with the ISP.
2. An organization applies for a class C website of 201.96.68.0, try to divide it into 6 logical subnets, and complete the following requirements:
(1). Calculate the total number of lost IP addresses after subnetting.
(2). Write down the start and end IP addresses of each subnet.
(3). Write out the subnet mask of the subnet.
computer network
1. Multiple choice questions ( 1 point for each question)
1. The predecessor of Internet is ( C ) .
A、Intranet B、Ethernet C、ARPAnet D、Cernet
2. The core protocol of the Internet is ( B ) .
A、X.25 B、TCP/IP C、ICMP D、UDP
3. Service and agreement are two completely different concepts. The following statements about them are wrong ( D ) .
A. The agreement is horizontal, that is, the agreement is the rule that controls the communication between peer entities. The service is vertical, that is, the service is provided by the lower layer to the upper layer through the interlayer interface.
B. Under the control of the protocol, the communication between two peer entities enables this layer to provide services to the upper layer. To implement the protocol of this layer, the services provided by the lower layer also need to be used.
C. The implementation of the protocol ensures that services can be provided to the upper layer.
D. OSI refers to the data unit exchanged between layers as a protocol data unit PDU .
4. Communication between TCP/IP processes often uses the client / server method . The following description of the client and server is wrong .
A. The client and the server refer to the two application processes involved in the communication.
B. The client / server method describes the relationship between the service and the serviced process.
C. The server is the service requester, and the client is the service provider.
D. A client program can communicate with multiple servers.
7. A total of 4 stations carry out CDMA communication. The chip sequence of 4 stations is: a : ( -1 -1 -1 +1 +1 -1 +1 +1 ) b : ( -1 -1 +1 -1 +1 +1 +1 -1 ) c : ( -1 +1 -1 +1 +1 +1 -1 -1 ) d : ( -1 +1 -1 -1 -1 -1 +1 -1 ) Now receive such chip sequence: ( - 1 +1 -3 +1 -1 -3 +1 +1 ), then ( A ) sends 1 .
A , a and d B , a C , b and c D , c
8. The LAN standardization work is formulated by ( B ) .
A、OSI B、IEEE C、ITU-T D、CCITT
9. The transmission in the computer is ( A ) transmission, while the transmission on the communication line is ( A ) transmission.
A , parallel, serial B , serial, parallel C , parallel, parallel D , serial, serial
11. In the local area network architecture ( B ) is divided into two sublayers , MAC and LLC .
A , physical layer B , data link layer C , network layer D , transport layer
12. The following statement about network interconnection equipment is wrong is C.
A. Transponders and hubs can be used to extend the LAN at the physical layer.
B. A bridge can be used to extend the LAN at the data link layer.
C. The Ethernet switch is essentially a multi-port bridge, working at the network layer
D. Routers are used to interconnect different networks and are network layer devices.
13. There are 10 stations connected to the Ethernet. If 10 stations are connected to a 10Mbit/s Ethernet hub , the bandwidth each station can get is ( A ) ; if 10 stations are connected to a 10Mbit/s Ethernet switch , each station can get The bandwidth is ( A ) .
A. 10 stations share 10Mbit/s , and each station exclusively occupies 10Mbit /s
B. 10 stations share 10Mbit/s , 10 stations share 10Mbit /s
C. Each station exclusively occupies 10Mbit/s , and each station exclusively occupies 10Mbit/s
D. Each station exclusively occupies 10Mbit/s , and 10 stations share 10Mbit/s
14. The following statement about virtual local area network ( VLAN) is wrong D.
A. VLAN is a logical group composed of some LAN segments that has nothing to do with physical location .
B. VLAN can be realized conveniently by using Ethernet switches .
C. The workstations of each VLAN can be in different local area networks.
D. Virtual local area network is a new type of local area network.
15. Regarding the wireless local area network, which of the following statements is wrong is D.
A. Wireless local area networks can be divided into two categories, namely those with fixed infrastructure and those without fixed infrastructure.
B. Wireless local area network without fixed infrastructure is also called ad hoc network.
C. The MAC layer of the wireless LAN with fixed infrastructure cannot use the CSMA/CD protocol, but the CSMA/CA protocol.
D. The mobile ad hoc network is the same as the mobile IP .
16. The concept of grouping is used in ( C ) layer.
A , physical layer B , data link layer C , network layer D , transport layer
17. The frame relay network is a kind of ( A ) .
A , wide area network B, local area networkC,ATMnetworkD, Ethernet
19. The following statement about IP address and hardware address is wrong ( D ) .
A. In LAN, hardware address is also called physical address or MAC address.
B. The hardware address is the address used by the data link layer and the physical layer, and the IP address is used by the network layer and the above layers.
C. The IP address cannot be directly used for communication, and the hardware address must be used to transmit data frames on the link of the actual network .
D、RARP是解决同一个局域网上的主机或路由器的IP地址和硬件地址的映射问题。
20、关于互联网中IP地址，下列叙述错误的是( D )。
A、在同一个局域网上的主机或路由器的IP地址中的网络号必须是一样的。
B、用网桥互连的网段仍然是一个局域网，只能有一个网络号。
C、路由器总是具有两个或两个以上的IP地址。
D、当两个路由器直接相连时，在连线两端的接口处，必须指明IP地址。
21、关于因特网中路由器和广域网中结点交换机叙述错误的是( C )。
A、路由器用来互连不同的网络，结点交换机只是在一个特定的网络中工作。
B、路由器专门用来转发分组，结点交换机还可以连接上许多主机。
C、路由器和结点交换机都使用统一的IP协议。
D. The router finds the next hop (that is, the next router) according to the destination network address, and the node switch finds the next hop (that is, the next node switch) according to the switch number that the destination station is connected to.
22. The data units transmitted in the physical layer, data link layer, and network layer of the OSI reference model are A respectively .
A , bit, frame, packet B, bit, packet, frameC, frame, packet, bitD, packet, bit, frame
23. Regarding CIDR without classification addressing , which of the following statements is wrong is C.
A. CIDR uses " network prefixes " of various lengths to replace network numbers and subnet numbers in classified addresses.
B. CIDR combines consecutive IP addresses with the same network prefix into a "CIDR" address block.
C. The shorter the network prefix, the fewer addresses the address block contains.
D. Using CIDR , multiple matching results may be obtained when searching the routing table, and the route with the longest network prefix should be selected from the matching results. Because the longer the network prefix, the more specific the route.
24. The following statement about Internet routing protocols is wrong .
A. The Internet uses a static, hierarchical routing protocol.
B. RIP is a routing selection protocol based on distance vectors. RIP selects a route (shortest route) with the least number of routers to the destination network .
C. The main feature of OSPF is the use of a distributed link state protocol, and all routers can eventually establish a link state database (topological structure diagram of the entire network).
D. BGP -4 adopts path vector routing protocol. The network reachability information exchanged by BGP is the sequence of autonomous systems that need to pass through to reach a certain network.
25. In TCP , the establishment of the connection adopts the method of ( C ) handshake .
A , once B , twice C , three times D , four times
26. Which of the following protocols belongs to the application layer protocol is C.
A , IP , TCP , and UDP B , ARP , IP , and UDP
C , FTP , SMTP and TELNET D,ICMP,RARPandARP network layer protocol
27. The application program for checking network connectivity is A.
A、PING B、ARP C、NFS D、DNS
28. C is used for WWW transmission control in the following protocol .
A、URL B、SMTP C、HTTP D、HTML
29. In the Internet domain name system, sub-domains can be divided under the domain , and domain names at all levels are separated by dots, according to D.
A. Arrange in 4 layers in a way of getting smaller and smaller from left to right B. Arrange in multiple layers in a way of getting smaller and smaller from left to right
C. Arrange in 4 layers in the way of getting smaller and smaller from right to left D. Arrange in multiple layers in the way of getting smaller and smaller from right to left 30. In the public key cryptosystem, B is not disclosed .
A , public key B , private key C , public key and encryption algorithm D , private key and encryption algorithm
31. A sends a message to B through the computer network, saying that he agrees to sign a contract . Then A went back on his word and refused to admit that he had sent the message. In order to prevent this from happening, ( D ) technology should be adopted in computer network .
A. Message authentication B. Data encryption C. Firewall D. Digital signature
32. The path selection function is completed in C of the OSI model .
A , physical layer B , data link layer C , network layer D , transport layer
33. At the level of the TCP/IP protocol family, the problem of communication between computers is solved in ( B ) .
A. Network interface layer B. Internet layer C. Transport layer D. Application layer
34. The English abbreviation for Internet service provider is D.
A、DSS B、NII C、IIS D、ISP
35. Applicable standard of CSMA/CD bus network ( A ) .
A. IEEE802.3 B. IEEE802.5 C. IEEE802.6 D. IEEE802.11
36. A computer network system in a building belongs to B.
A、PAN B、LAN C、MAN D、WAN
37. The basic signal unit that carries information is A.
A. , symbol B., bitC,.data transmission rateD, bit error rate
38. The communication between the computer and the printer belongs to ( A ) .
A , simplex communication B , half-duplex communication C , full-duplex communication D , neither
39. The following software that does not belong to the network operating system is B.
A、Netware B、WWW C、Linux D、Unix
40. To connect a local area network to the Internet , the preferred device is A.
A , router B , repeater C , bridge D , gateway
41. A switch with a rate of 100M has 20 ports , and the transmission rate of each port is A.
A , 100M B , 10M C , 5M hub D , 2000M
42. The best performance of the following transmission media is ( C ) .
A , coaxial cable B , twisted pair C , optical fiber D , telephone line
43. The highest three bits of the class C IP address are B from high to low .
A 、010 B 、110 C 、100 D 、101
44. The following is C which does not belong to the wide area network .
A. ATM network B. Frame relay network C. Ethernet D. X.25 packet switching network
45. PPP is a ( B ) -oriented protocol .
A , bit B , character C , word D , number
46. The MAC layer in the local area network corresponds to the OSI reference model ( B ) .
A , physical layer B , data link layer C , network layer D , transport layer
47. The service type provided by the IP protocol is B.
A. Connection-oriented datagram service B. Connectionless datagram service
C. Connection-oriented virtual circuit service D. Connectionless virtual circuit service
48. The router works in ( B ) and is used to connect multiple logically separated networks.
A , physical layer B , network layer C , data link layer D , transport layer
49. The meaning of hypertext is C.
A. The text contains sound B. The text contains binary numbers
C. The text contains links to other texts D. The text contains images
50. The application layer protocol responsible for email transmission is A.
A 、SMTP B 、PPP C 、IP D 、FTP
51. For the host domain name for.zj.edu.cn , ( B ) indicates the host name .
A 、zj B 、for C 、edu D 、cn
52. The remote login uses the following D protocol.
A 、SMTP B 、FTP C 、UDP D 、 TELNET
53. The file transfer uses the following B protocol.
A 、SMTP B 、FTP C 、SNMP D 、TELNET
54. The twisted pair transmission medium is to twist two wires together, which can reduce ( D ) .
A. Attenuation during signal transmission B. Interference from external signals
C. Signal leakage D. Mutual crosstalk between signals
55. The transmission medium is the (A) path between the sender and the receiver in the communication network .
A , Physical B , Logical C , Virtual D , Digital
56. The bridge works ( C ) to connect two local area networks together and forward frames according to MAC addresses. P102
A , physical layer B , network layer C , data link layer D , transport layer
57. The following four IP addresses ( B ) are illegal host addresses.
A、10011110.11100011.01100100.10010100
B、11101110.10101011.01010100.00101001
C、11011110.11100011.01101101.10001100
D、10011110.11100011.01100100.00001100
58. The equipment at both ends of the data link is C.
A , DTE B , DCE C , DTE or DCE D , DTE and DCE
59. The media access control mode adopted by Ethernet is A.
A 、CSMA/CD B、 Token RingC、 Token BusD、CSMA/CA
60. When two computers use telephone lines to transmit data signals , the necessary equipment is B.
A , network card B , modem C , repeater D , coaxial cable
61. The ICMP protocol is located at A.
A , network layer B, transport layerC, application layerD, data link layer
62. The network bridge is a device for ( D ) .
A , physical layer B , network layer C , application layer D , data link layer
63. The PPP agreement is a ( B ) agreement .
A , physical layer B , data link layer C , network layer D , application layer
The transmission medium used by 64 and 100base -T is C.
A , coaxial cable B , optical fiber C , twisted pair D , infrared
65 ．If the network layer uses datagram services , then B.
A. Routing is only done once when the connection is established B. Routing is done for each incoming packet
C. Do new routing only when the network is congested D. No need to do routing
66. In the OSI model, the relationship between layer N and the layer N + l above it is ( A ) .
A , layer N provides services for layer N + 1 B,layerN+1adds a header to the information received from layerN
Layer C and N use the services provided by layer N + 1 Layer D and layer N have no effect on layer N + 1
70. The address "128.10.0.0" is ( B ) address.
A , A class B , B class C , C class D , D class
71. The protocol for converting IP addresses into physical addresses is C.
P-152 A、IP B、ICMP C、ARP D、RARP
72. The protocol for converting physical addresses into IP addresses is D.
P-153 A、IP B、ICMP C、ARP D、RARP
7 3. In a network with a small MTU , the datagram needs to be divided into several smaller parts for transmission. This smaller part is called B.
A , Group B , Slice C , Segment D , Section
74. Use ( C ) of IP protocol to control the time delay of data transmission.
A , service type B , identification C , survival time D , destination IP address
75. Computer network is a comprehensive technology, and its main technology is B.
A. Computer technology and multimedia technology B. Computer technology and communication technology
C. Electronic technology and communication technology D. Digital technology and analog technology
76. In order to realize high-efficiency data transmission, TCP/IP adopts UDP protocol in the transport layer , and the reliability of its transmission is provided by ( A ) .
A , application process B,TCP C,DNS D,IP
77. At present, the wide area network that actually exists and is used basically adopts C.
A , bus topology B , ring topology C , mesh topology D , star topology
78. In the OSI hierarchy, the actual communication is carried out between ( A ) entities .
A , physical layer B , data link layer C , network layer D , transport layer
79. The IP address 192.1.1.2 belongs to ( D ) , and its default subnet mask is () .
Class A , B , 255.255.0.0 B , Class A , 255.0.0.0 C ,
Class C , 255.255.0.0 Class D , Class C , 255.255.255.0
80. Among the following items, ( D ) is not a function of X.25 .
A. Virtual circuit service B. Multiplexing C. Flow and error control D.Datagram service
2. Fill in the blanks ( 1 point for each blank)
1. Computer network can be divided into wide area network , local area network and metropolitan area network according to the scope of function .
2. Three types of wired transmission media commonly used in computer networks are twisted pair, coaxial cable, and optical fiber .
3. There are three main switching technologies for data switching: line switching, message switching, and packet switching .
4. The two most important performance indicators of computer networks are bandwidth and delay .
5. The three elements of a network protocol are syntax , semantics, and timing .
6. The data transmission system is divided into two types: analog transmission system and digital transmission system.
8. The unit of information transmission rate is bit / second , and the unit of symbol transmission rate is baud .
9. Data communication can be divided into two categories: synchronous communication and asynchronous communication .
10. A station in a WLAN with a fixed infrastructure detects that the channel is busy, either because the physical layer carrier sense detects that the channel is busy, or because the MAC layer virtual carrier sense mechanism indicates that the channel is busy.
11. CIDR combines consecutive IP addresses with the same network prefix into a "CIDR" address block, and the routing table uses the CIDR address block to find the destination network. This kind of address aggregation is often called route aggregation , also known as forming a supernet.
12. Compared with IPV4 , the address of IPV6 is increased to 128 bits . For the convenience of reading and manipulating these addresses, IPV6 uses colon hexadecimal notation.
13. The transport layer provides logical communication between application processes, and the network layer provides logical communication between hosts .
14. The reliability of TCP transmission is due to the use of sequence number and confirmation number .
15. The end-to-end round-trip delay 2t of Ethernet is called the contention period , also known as the collision window . Ethernet takes the length of the 51.2u contention period, and stipulates that any frame with a length less than 64 bytes is an invalid frame .
17. The domain name system DNS of the Internet is an online distributed database system.
18. The interface characteristics of the physical layer include mechanical characteristics, electrical characteristics, functional characteristics and protocol characteristics .
19. Packet transmission in the network can be transmitted in two ways: datagram and virtual circuit .
20. In the TCP/IP network, the TCP protocol works at the transport layer , and the FTP protocol works at the application layer.
22. Time division multiplexing technology can be divided into synchronous time division multiplexing and asynchronous time division multiplexing .
2 3. Principles of computer network The system structure is divided into five layers, which are application layer , transport layer, network layer, data link layer and physical layer.
24. In the OSI reference model , the unit of data transmitted on the peer-to-peer layer is called the data transmission unit PDU of this layer .
25. The rules, standards or conventions established for data exchange in the network are called protocols .
26. The TCP/IP model is divided into four layers, which are the application layer, the transport layer, the Internet layer, and the host-network layer .
28. The wide area network is composed of some junction switches and links connecting these switches .
29. To convert the host name into an IP address , use the DNS protocol,
To convert an IP address into a MAC address , use the ARP protocol.
30. The PING command uses ICMP Echo request and Echo reply messages.
31. The TCP/IP transport layer has two different protocols, namely User Datagram Protocol UDP and Transmission Control Protocol TCP .
32. In the TCP/IP network , the physical address is related to the data link layer , the logical address is related to the network layer, and the port address is related to the transport layer .
33. Symbol / second is the rate unit of symbol transmission , and bit is the unit of information volume.
34. In the virtual circuit service, before any transmission starts, a connection must be established first .
35. Regarding the term 10base-T , 10 indicates a transmission rate of 10Mbit/s , base indicates that the signal on the connection line is a baseband signal , and T indicates a twisted pair .
36. In order to facilitate routing selection, the Internet divides the entire network into many smaller units, namely AS . Therefore, routing protocols are also divided into two categories, namely Interior Gateway Protocol IGP and Exterior Gateway Protocol EGP .
37. The most representative interior gateway protocols are OSTP using link state routing algorithm and RIP using distance vector routing algorithm .
38. Routing algorithms are usually divided into two categories, namely static and dynamic .
40. Among classified IP addresses, class D addresses belong to multicast addresses .
43. Channel multiplexing includes time-division , frequency-division multiplexing, code-division multiplexing, and wavelength-division multiplexing .
45. From the nature of the multiplexing scheme, frequency division multiplexing is more suitable for analog transmission , while time division multiplexing is more suitable for digital transmission.
46. A TCP connection process is divided into three stages, namely, connection establishment, data transmission, and connection release .
47. The signal transmitted in the computer is a digital signal , while the signal transmitted by the public telephone transmission system is an analog signal .
48. There are three ways to modulate a digital signal into an analog signal, namely frequency modulation, amplitude modulation, and phase modulation.
51. The dedicated IP address can only be used as a local address and not as a global address.
52. The MAC sublayer of Gigabit Ethernet still uses the CSMA/CD protocol , and supports half-duplex and full-duplex communication.
54. In the local area network , the hardware address is also called the physical address or MAC address .
55. The local area network adopts a flat address structure , and a hierarchical address structure is generally adopted in a wide area network .
56. ATM is a connection- circuit switching and packet switching
Computer major 2002 "Computer Network" course mid-term exam papers
1. Multiple-choice questions (1 point for each question, 30 points in total) Choose the most appropriate answer from the four options for the following questions A), B), C), and D), and fill in the corresponding position on the answer sheet. Answer Not scored on the test paper.
1. Currently, the most popular Ethernet networking topology is (C).
A) bus structure B) ring structure C) star structure D) mesh structure
2. The switching equipment in the public switched telephone network (PSTN) provides (D) switching mode.
A) packet B) message C) cell D ) circuit
3. The main elements of the network protocol are (C).
A) Data format, encoding, signal level B) Data format, control information, speed matching C
) Syntax, semantics, synchronization D) Encoding, control information, synchronization
4. Increasing the link rate can reduce data (D).
A) propagation delay B) queuing delay C) waiting delay D ) sending delay
5. The world's first packet switching network put into operation is (C).
A) Telecommunications network B) Ethernet C) ARPANET D) Internet
6. In the star LAN structure , the device connecting the file server and the workstation is (D).
A) Modem B) Bridge C) Router D ) Hub
7. In the OSI seven-layer structure model, it is (B) between the data link layer and the transport layer .
A) physical layer B) network layer C) session layer D) presentation layer
8. The path selection function is completed in (C) of the OSI model .
A) physical layer B) data link layer C ) network layer D) transport layer
9. In the repeater system, the repeater is in (A)
A ) physical layer B) data link layer C) network layer D) high layer
10. Requirements for interconnection of various networks at the physical layer (A)
A ) The data transmission rate and link protocol are the same B) The data transmission rate is the same, but the link protocol can be different
C) The data transmission rate can be different, but the link protocol is the same D) The data transmission rate and link protocol can both be different
13. In digital communication, the function of the transmission medium is (A).
A) pass a signal from one end to the other B) correct errors in transmission
C) Automatically adjust the signal form according to the line condition D) Send information between the source station and the destination station.
16. Among the following gateways, (B) realize network interconnection at the data link layer .
A) Repeater B ) Bridge C) Router D) Gateway
17. Signal bandwidth refers to (B).
A) the ability of the signal to represent data B ) the width of the frequency spectrum the signal has C) the number of frequencies D) the transmission capacity of the medium
18. The method of dividing channels by frequency is called (A).
A）FDM B）TDM C）SDTM D）WDM
20. In the stop-and-wait protocol algorithm , the purpose of using frame numbers is (C).
A) Handling loss of data frames B) Handling loss of acknowledgment frames C ) Handling duplicate frames D) Handling errors
21. In the continuous ARQ protocol, when the number of sliding window numbers is n, the maximum size of the sending window is ( A ).
A ） 2n-1 B) 2n C) 2n-1 D) 2n
22. For baseband CSMA/CD, in order to ensure that the sending station can detect possible collisions during transmission, the transmission delay of the data frame must be at least equal to the signal propagation delay ( B )
A) 1 times B) 2 times C) 4 times D) 2.5 times
23. The optical fiber is composed of three layers of materials, and the function of the cladding is (B).
A) Enhance the tensile strength B) Reduce the refractive index of light C) Protect the fiber core D) Ground the optical signal
24. The network transmission delay is the smallest (A).
A ) circuit switching B) message switching C) packet switching D) cell switching
28. Divide the network 202.112.78.0 into multiple subnets, and the subnet mask is 255.255.255.192, then the sum of the available host addresses in each subnet is (B)
A） 254 B） 252 C） 128 D）114
29. Which of the following will not generate ICMP error messages (D).
A) The router cannot choose the route correctly
B) The router cannot deliver the datagram
C) The router detects an abnormal condition preventing it from forwarding the datagram
D) An ICMP error report message has been generated
2. Fill in the blanks (1 point for each blank)
1. The time required for a message to be transmitted from one end of the network to the other is called delay. The delay in the network is mainly composed of propagation delay, sending delay and queuing delay .
2. In different layers of OSI, the transmitted data forms are different. The data unit transmitted by the physical layer is a bit , the data unit of the data link layer is a frame , the data unit of the network layer is a packet , and the transport layer transmits The unit of data is the message.
3. In IpV4, the IP address of all hosts in the broadcast network is 255, which means that the host IP address of this network is 0, and the IP address used for the loopback test is 127 .
4. The key points of the CSMA/CD protocol are multi-point access, carrier sense and collision detection .
6. A virtual local area network (VLAN) is a logical group composed of some LAN segments that has nothing to do with physical location . The main principle of virtual local area network control "broadcast storm" is to limit the number of workstations receiving broadcasts in the local area network .
7. Try to explain what 100BASE-T means. Use twisted pair wire as the transmission medium 100Mbps baseband transmission network .
4. Short answer questions (30 points)
3. A certain unit is assigned a class B IP address, and its net-id is 129.250.0.0. The unit has 4000 machines distributed in 16 different locations. Please analyze:
(1) Is it appropriate to choose the subnet mask as 255.255.255.0?
Answer: The subnet mask used in the question is 255.255.255.0. It means that in the last 16 bits, the first 8 bits are used to divide the subnet, and the last 8 bits are used to determine the host, then each subnet has a maximum of 28-2=254 hosts. It can be seen that the hosts in the 16 subnets have a total of 16×254=4064 hosts. The question shows that the unit has 4,000 machines distributed in 16 different locations. It did not say how many machines each of the 16 different locations had. therefore:
1) If it is "evenly" distributed in 16 subnets, that is, the number of hosts in any one of the 16 subnets does not exceed 254 hosts, then it is possible to choose this subnet mask;
2) If the number of machines in a subnet exceeds 254, it is inappropriate to choose such a subnet mask.
(2) If appropriate, try to assign a subnet number to each location, and calculate the minimum and maximum IP addresses of each host.
Answer: The design "borrows" 4 bits in the network address field and subnet before the host number as 16 subnet addresses. These 16 locations can be assigned subnet numbers from 129.250.nnn.0 to 129.250.nnn.255, where nnn can be 0~15, 16~31, 32~47, 48~63, 64~79, 80~95, 96~111, 112~127, 128~143, 144~159, 160~175, 176~191, 192~207, 208~223, 224~239, 240~255. One of these subnets can be designed in groups or 16 of them can be selected respectively. The number of hosts in each subnet is 1 to 254.
Computer Network Final Exam Questions and Answers
Fill in the blanks (1 point for each blank, 30 points in total)
1. In the definition of a computer network, a computer network includes multiple computers with autonomous functions ; the organic connection of many computers must follow the prescribed conventions and rules, that is, communication protocols; the most basic feature of a computer network is resource sharing
2. Common computer network topologies are: bus, star, mesh
3. There are two types of commonly used transmission media: wired and wireless. Wired media include twisted pair, coaxial cable, and optical fiber.
4. The network can be divided into wide area network, metropolitan area network and local area network according to the scope of coverage .
5. The TCP/IP protocol reference model is divided into 4 layers , of which layers 3 and 4 are the transport layer and the application layer.
6. The email system provides a store-and-forward service , and the WWW service mode is _B/S
10. There are two synchronous technologies for data transmission : synchronous transmission and asynchronous transmission .
12. Multiplexing technology is to make multiple signals use one line for transmission, or combine multiple signals for transmission on one physical channel to make full use of the capacity of the channel. Multiplexing is divided into: frequency division multiplexing_, wavelength division multiplexing_, time division multiplexing and code division multiplexing
13. VLAN (Virtual Local Area Network) is a new data exchange technology that divides the LAN logically into network segments instead of physically dividing network segments to realize virtual working groups.
2. Multiple choice questions (2 points for each question, 30 points in total)
14. The computer network topology is to express the ____B_____ between entities in the network through the geometric relationship between the nodes in the network and the communication lines.
A. Online relationship B. Structural relationship C. Primary and secondary relationship D. Hierarchical relationship
17、127.0.0.1属于哪一类特殊地址（ B ）。
A、广播地址B、回环地址C、本地链路地址D、网络地址
18、HTTP的会话有四个过程，请选出不是的一个。（D ）
A、建立连接B、发出请求信息C、发出响应信息D、传输数据
19、在ISO/OSI参考模型中，网络层的主要功能是_Ｂ
A、提供可靠的端—端服务，透明地传送报文 B、路由选择、拥塞控制与网络互连
C、在通信实体之间传送以帧为单位的数据
D、数据格式变换、数据加密与解密、数据压缩与恢复
21、以下选项不属于以太网的“５４３”原则是指？__D__
A、５个网段 B、４个中继器 C、３个网段可挂接设备 D、５个网段可挂接
22、既可应用于局域网又可应用于广域网的以太网技术是D
A、以太网 B、快速以太网 C、千兆以太网 D、万兆以太网
24、要把学校里行政楼和实验楼的局域网互连,可以通过（ A ）实现。
A、交换机 B、MODEM C、中继器 D、网卡
25、以下哪一类IP地址标识的主机数量最多？（ D ）
A、D类 B、C类 C、B类 D、A类
26、子网掩码中“1”代表（ B ）。
A、主机部分 B、网络部分 C、主机个数 D、无任何意义
27、给出B类地址190.168.0.0及其子网掩码255.255.224.0，请确定它可以划分几个子网？（B ）
A、8 B、6 C、4 D、2
28、TCP/IP体系结构中与ISO-OSI参考模型的1、2层对应的是哪一层（A ）
A、网络接口层 B、传输层 C、互联网层 D、应用层
三、名词解释题（每题2分，共 10 分）
29、UTP 非屏蔽双绞线
30、DNS 域名系统
31、FTP文件传输
32、SMTP简单邮件传输协议
四、简答题（共 30 分）
35、试论述OSI参考模型和TCP/IP模型的异同和特点。（8分）
相同点：两个协议都分层；OSI参考模型的网络层与TCP/IP互联网层的功能几乎相同；以传输层为界，其上层都依赖传输层提供端到端的与网络环境无关的传输服务。
不同点：TCP/IP没有对网络接口层进行细分；OSI先有分层模型，后有协议规范；OSI对服务和协议做了明确的区别，而TCP/IP没有充分明确区分服务和协议。
36.网络安全面临的威胁主要有哪些。（6分）
1系统漏洞2黑客攻击3病毒入侵4网络配置管理不当
计算机网络技术试题
第一部分 选择题
一、单项选择题(本大题共20小题，每小题1分，共20分)在每小题列出的四个选项中只有一个选项是符合题目要求的，请将正确选项前的字母填在题后的括号内。
1.采用全双工通信方式，数据传输的方向性结构为( A )
A.可以在两个方向上同时传输 B.只能在一个方向上传输
C.可以在两个方向上传输，但不能同时进行 D.以上均不对
4. Using phase-amplitude modulation PAM technology can increase the data transmission rate. For example, using 8 phases, and each phase takes 2 amplitude values, so that the number of bits in a binary number represented by a symbol is ( D )
A. 2 digits B. 8 digits C. 16 digits D. 4 digits
5. If the network shape is a closed ring composed of sites and links connecting the sites , then this topology is called ( C )
A. Star topology B. Bus topology C. Ring topology D. Tree topology
12. If the bit string "01011111001" appears in the data segment of the HDLC frame, the output after bit filling is (B)
A. 010011111001 B. 010111110001 C. 010111101001 D. 010111110010
13. For the sliding window protocol of out-of-order reception, if the number of serial numbers is n, the maximum size of the sending window is ( C )
A. 2n-1 B. 2n C. 2n-1 D. 2n-1
14. Among the following items, the one that is not a characteristic of datagram operation is (C)
A. Each packet itself carries enough information that its transmission is handled individually
B. During the entire transmission process, there is no need to establish a virtual circuit
C. Make all packets reach the destination end system in order
D. Network nodes must make routing selections for each packet
15. The services provided by TCP and IP in the TCP/IP architecture are ( D )
A. Link layer service and network layer service B. Network layer service and transport layer service
C.运输层服务和应用层服务 D.运输层服务和网络层服务
16.对于基带CSMA/CD而言，为了确保发送站点在传输时能检测到可能存在的冲突，数据帧的传输时延至少要等于信号传播时延的( B )
A. 1倍 B. 2倍 C. 4倍 D. 2.5倍
17.以下各项中，是令牌总线媒体访问控制方法的标准是( B)
A. IEEE802.3 B. IEEE802.4 C. IEEE802.6 D. IEEE802.5
18.采用曼彻斯特编码，100Mbps传输速率所需要的调制速率为( A )
A. 200MBaud B. 400MBaud C. 50MBaud D. 100MBaud
19.若信道的复用是以信息在一帧中的时间位置(时隙)来区分，不需要另外的信息头来标志信息的身分，则这种复用方式为( C )
A.异步时分复用 B.频分多路复用 C.同步时分复用 D.以上均不对
20.由于帧中继可以使用链路层来实现复用和转接，所以帧中继网中间节点中只有( A )
A.物理层和链路层 B.链路层和网络层 C.物理层和网络层 D.网络层和运输层
第二部分 非选择题
二、填空题(本大题共17小题，每空0.5分，共20分)
22.计算机网络的功能主要表现在硬件资源共享、软件资源共享和_用户间信息交换三个方面。
23.串行数据通信的方向性结构有三种，即单工、半双工、 全双工
24.模拟信号传输的基础是载波，载波具有三个要素，即幅度 、频率 、相位。数字数据可以针对载波的不同要素或它们的组合进行调制，有三种基本的数字调制形式，即移幅键控法ASK、 移频键控法FSK 、 移相键控法PSK
25.最常用的两种多路复用技术为_频分多路复用FDM 、 时分多路复用TDM，其中，前者是同一时间同时传送多路信号，而后者是将一条物理信道按时间分成若干个时间片轮流分配给多个信号使用。
26.HDLC有三种不同类型的帧，分别为_信息帧(I帧) 、监控帧(S帧) 和无编号帧(U帧)。
27.X.25协议的分组级相当于OSI参考模型中的 网络 层，其主要功能是向主机提供多信道的 虚电路 服务。
29.OSI的会话层处于运输 层提供的服务之上，为_表示层提供服务。
30.会话层定义了两类同步点，分别为_主同步点和次同步点。其中后者用于在一个对话单元内部实现数据结构化。
31.OSI表示层的主要功能为语法转换 、语法协商和连接管理。
32.FTAM是一个用于传输、访问 和管理开放系统中文件的信息标准。它使用户即使不了解所使用的实际文件系统的实现细节，也能对该件系统进行操作。
33.在TCP/IP层次模型中与OSI参考模型第四层(运输层)相对应的主要协议有TCP和UDP，其中后者提供无连接的不可靠传输服务。
34.在TCP/IP层次模型的第三层(网络层)中包括的协议主要有IP、ICMP、ARP 、RARP。
35.载波监听多路访问CSMA技术，需要一种退避算法来决定避让的时间，常用的退避算法有非坚持、1—坚持、 P—坚持三种。
37. Every webpage (Home Page) on the WWW has an independent address, and these addresses are called Uniform Resource Locators (URL) .
3. Explanation of terms (there are 4 sub-questions in this major topic, 2 points for each sub-question, 8 points in total)
38. Channel capacity
The maximum data transmission rate of the channel is the limit of the channel's data transmission capability, and the unit is bits per second (bps).
39. Non-return-to-zero code NRZ
Either current is emitted or not (unipolar) and positive or current is emitted (bipolar) for the entire time of a symbol.
Each code occupies the width of the entire code unit. This encoding method is called non-return-to-zero code NRZ.
40. Multiplexing
In data communication or computer network systems, the bandwidth or capacity of the transmission medium often exceeds the requirements for transmitting a single signal. In order to effectively use the communication line, one channel can be used to transmit multiple signals. This method is called channel multiplexing , referred to as multiplexing (Multiplexing).
41. Parity code
The parity check code is a coding method that makes the number of "1" in the code word always odd or even by adding 1 redundant bit. This is an error detection code.
4. Short answer questions (this major question has 3 sub-questions, each with 4 points, a total of 12 points)
42. Briefly describe the P-adhere to algorithm rules of CSMA technology.
(1) Monitor the bus. If the bus is idle, send it with the probability of P, and delay one time unit with the probability of (1-P) (twice the maximum propagation delay).
(2) After a delay of one time unit, repeat step (1).
(3) If the bus is busy, continue to monitor until the bus is free and repeat step (1).
44. Briefly describe the preparation work required to connect to the Internet using "dial-up networking".
(1) Select a suitable ISP and obtain an Internet account through the ISP;
(2) Prepare a modem and a telephone line that can dial the ISP;
(3) Install "Dial-Up Networking";
(4) Install the TCP/IP protocol and bind it to the "dial-up network adapter";
(5) Input TCP/IP related information;
(6) Use "dial-up networking" to establish a connection with the ISP.
1. Explanation of terms (write out the full name in Chinese and English)
1、DNS
DNS is the abbreviation of Domain Name System (Domain Name System)
2、SMTP
SMTP (Simple Mail Transfer Protocol) is a simple mail transfer protocol
3、FTP
FTP is the English abbreviation of File Transfer Protocol (File Transfer Protocol)
4、HTTP
Hypertext Transfer Protocol (HTTP, HyperText Transfer Protocol)
2. Questions and answers
1. Briefly describe the full names and differences between TCP and UDP.
UDP: short for User Datagram Protocol, the Chinese name is User Datagram Protocol
TCP: Transmission Control Protocol Transmission Control Protocol
The main difference between UDP and TCP protocols is that they are different in how to achieve reliable transmission of information
2. Briefly describe the classification of IP addresses
3. Calculation questions
Mask calculation. A college obtains an address 202.202.135.0 from the school network center and needs to divide 10 subnets. What should be the subnet mask? (Please write down the complete calculation process)
Divide 10 subnet masks, according to the formula: 2 to the Nth power>=10, so N=4, borrow 4 bits.
Furthermore: 202.202.135.0 is a class C address,
So: only borrow 4 bits from the last byte: 202.202.135.00000
So the subnet mask is 255.255.255.240 (borrow 4 bits 1111 0000)