When recruiting computer majors, institutions in Qinghai Province need to test their professional knowledge. I don't know what the main aspects are, please answer!

The audit materials for recruiting computer majors in public institutions are as follows:

First, the concept of computer network

Through well-functioning network software, computer systems with independent working ability distributed in different geographical areas can realize resource sharing and data communication through communication equipment and lines. As can be seen from the definition, there are three problems involved: (1) At least two computers are interconnected. (2) Communication equipment and media. (3) Network software, communication protocol and operating system

Each manufacturer makes different network equipment. In order to communicate between them, they must abide by certain rules, that is, protocol representation.

Second, the composition of the computer network

It consists of hardware system and software system.

1, network hardware

Connect equipment, service devices, workstations, workstations.

( 1)

Server: It is the core of the whole network. It not only manages the network, but also serves the network users. According to different functions, it can be divided into file server, print server, communication server and backup server. It is actually a well-configured computer.

(2) Workstation: a computer connected to a network server, which can realize resource sharing.

(3) Peripheral devices: devices used to connect servers and workstations. Play the role of communication.

2. Network software: comprehensively manage hardware to realize communication and resource sharing.

(1) network operating system

(2) Network communication software

Third, the role of computer networks.

The functions of computer networks are mainly manifested in the following aspects:

(1) data communication

(2) Centralized real-time control and management of distributed objects.

All kinds of information management systems, such as online information decision-making systems, enterprise (intranet) information management and the application of common C/S and B/S structures in office automation of government agencies, should carry out centralized database management.

(3) Resources * * * have functions.

Documents, printing, data and application software can enjoy services, and communication services and fax services can be established.

(4) Load balancing and distributed processing functions

Under the management of distributed operating system, a big task is broken down into small tasks and distributed to different computers on the Internet for execution.

(5) Comprehensive information service function

WWW, e-mail, BBS, e-commerce, virtual community, university, remote login, online meeting.

Fourth, the development of computer networks.

The development of computer network is now the fourth generation. In the early days, computers were highly concentrated and placed in a big house. Later, time-sharing and batch processing appeared, and the first generation of computer networks appeared in the 1950s.

1, the first generation computer network

It is composed of multiple terminals connected by a computer, such as the plane booking system in the United States.

2, the second generation computer network

The second generation computer network is a network in which many host computers are interconnected by communication lines. These main computers have autonomous processing ability, and there is no master-slave relationship between them. A network in which many host computers are interconnected is now commonly referred to as a computer network. The typical representative is ARPA network, which is mainly composed of four main nodes. It is also the Zou style of our current Internet development. There is a special communication processor in ARPA network, which is responsible for the interconnection of lines. This device is called (Interface Information Processor IMP). When the host wants to send a message, it only needs to send it to its associated IMP, and then IMP is responsible for finding the other party's IMP and sending it out. IMP uses the store-and-forward method and sends it when the line is idle. In this way, ARPA network has formed a two-level subnet structure. Communication sub-resources and resource subnets.

3. The Third Generation Computer Network-International Standardization Network

In the era of ARPA network, although the network is divided into communication subnet and resource subnet. However, the inconsistency of system structure and protocol standards between networks limits the development of computer networks. ISO, the international organization for standardization, issued "Open System Interconnection", which makes the interaction between networks possible. All communication devices, software and protocols follow the OSI model.

4, the fourth generation computer network

Nowadays, the network is already in the Internet era, and it is developing towards interconnection, high speed and broadband. Various applications on the Internet are also increasingly rich, such as virtual universities, virtual communities, e-commerce, video-on-demand systems and so on. It has had an important impact on our lives.

Verb (abbreviation for verb) Classification of computer networks

There are many standards for computer network classification, such as topology, transmission medium, application protocol, etc. However, these standards can only reflect the characteristics of a certain aspect of the network, and the classification standard that best reflects the essential characteristics of network technology is distribution distance, which can be divided into local area network, metropolitan area network, wide area network and Internet.

1. LAN: A minicomputer of several meters-10 km was developed after the popularization of a large number of microcomputers. It is easy to configure and has a high speed of 4 Mbps-2 Gbps.

Located in a building or a unit, there is no pathfinding problem, excluding the network layer. 2. MAN: 10 km- 100 km.

The LAN interconnection of a city adopts IEEE802.6 standard, 50 kbps- 100 kbps, which is located in a city. 3. Wide area network: also known as long-distance network, hundreds to thousands of kilometers.

It developed earlier, leased private lines, connected with lines through IMP, and formed a mesh structure, which solved the routing problem at the rate of 9.6 kbps-45 Mbps.

Such as CHINANET, CHINAPAC and CHINADDN of the Ministry of Posts and Telecommunications. 4. Internet: It is not a specific network technology, but an advanced technology that unifies different physical network technologies according to certain protocols. Common network communication protocols

First, the concept of agreement.

Different workstations and servers in the network can transmit data because of the existence of protocols. With the development of network, different developers have developed different communication methods. In order to make communication successful and reliable, all hosts in the network must use the same language, without dialects. Therefore, strict standards must be formulated to define every bit of every word in every data packet between hosts. These standards come from the efforts of many organizations for a common communication method (i.e. protocol). All these make communication easier.

Definition of protocol-some conventions that must be met to realize communication in computer networks.

Can be implemented in hardware and software.

OSI (Open Systems Interconnection) was proposed by ISO (International Organization for Standardization) in 1978. It defines the communication protocol of computer network architecture as seven layers: physical layer, data link layer, network layer, transport layer, session layer, presentation layer and application layer.

Many protocols have been developed, but only a few remain. There are many reasons to cancel those protocols-design a complete connection between this _ text _ source _ in _ expensive _ state _ learning _ network. TCP/IP was developed by MIT and some commercial organizations for the US Department of Defense in 1960s. Even if most networks are destroyed by nuclear attacks, TCP/IP can still maintain effective communication. ARPANET was developed based on this protocol and developed into a communication medium for scientists and engineers. TCP/IP has both scalability and reliability requirements. Unfortunately, speed and efficiency are sacrificed (but the development of TCP/IP is funded by the government). After the Internet became public, people began to discover the powerful functions of the World Wide Web. The universality of Internet is the reason why TCP/IP is still in use. Usually, without realizing it, users install TCP/IP stack on their own PC, which makes network protocol the most widely used protocol in the world. Five, how to choose the network communication protocol

The choice of network communication protocol affects the speed and performance of the network. When choosing, we should consider the scale, compatibility, convenience and speed of management of the network.

1, WINDOWS series network

If it is a small window.

NETBEUI protocol should be selected for NT server/workstation network, which is fast; If it is a large Internet connection, it is necessary to install TCP/IP. If the workstation of WIN95 only has TCP/IP installed, you can't join WINDOWS.

NT domain

2.NOVELL network

If the client wants to access NOVELL network, it will join IPX/SPX protocol.

3, WINDOWS, NOVELL network mixed.

IPX/SPX protocol, NETBEUI protocol and TCP/IP protocol must be added to the hybrid network.

Intransitive verb internet address

1, IP address: The Internet is interconnected by different physical networks, and the communication between computers in different networks must have corresponding address identifiers, which are called IP addresses. IP address provides a unified address format, which consists of 32 bits. Because binary is inconvenient to use, users use "dotted decimal" to represent it. The IP address uniquely identifies the network where the host is located and the location number in the network. IP address is divided into two parts: network number and host number. For example: IP address:192.168.0.1.

2. According to the size of the network, commonly used IP addresses are divided into the following three categories: A: This kind of address is characterized by starting with 0, the first byte represents the network number, and the second, third and fourth bytes represent the host number in the network. The number of networks is small, which can represent at most 126 network numbers, and each network can have at most 167772 14 hosts.

0 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * l— 126 0—255 0—255 1—254

B: This kind of address is characterized by starting with l0. The first and second bytes represent network numbers, and the second and third bytes represent host numbers in the network, which can represent at most 16384 network numbers, and each network can have at most 66534 host numbers.

10 * * * * * * * * * * * * * * * * * * * * * * 19 1 0-255 1.

C: This kind of address is characterized by starting with 1 10. The first, second and third bytes represent the network number, and the fourth byte represents the host number in the network. The number of networks is relatively large, with 2097 152 network numbers, and each network can have up to 254 host numbers.

1 10***** ******** ******** ******** 192—233 0—255 0—255 1—254

D and E: The first digit ranges of these two types of IP addresses are 224-239 and 240-254, which are reserved for future use. Other knowledge of computer network

A, the provisions of the IP address:

1, the network number cannot start with 127, and the first byte cannot be all zeros or all l.2. The host number cannot be all zeros or all 1. So there are no IP addresses of 255.255.255.255 and 0.0.0.0.

3. 127.0.0. 1 is the IP address of this machine and cannot be used as the IP address of the host on the network.

Second, subnet mask.

1, function: In order to quickly determine which part of an IP address represents the network number and which part represents the host number, and to judge whether two IP addresses belong to the same network, the concept of subnet mask is generated, and the subnet mask is given according to the format of the IP address.

2. The default subnet mask of Class A, Class B and Class C IP addresses is as follows:

A: 255 pounds. B: 255.255.0

3. Calculation of subnet mask:

The method of judging the network number and host number of an IP address by subnet mask is to AND the IP address with the corresponding subnet mask, so that the network number part and the host number part can be distinguished.

For example, 10.68.89. 1 is a class A IP address, then the default subnet mask is 255.0.0, o, which are all converted into binary and the network number is 10. Another example is 202.30. 152.3 and 202.30. 152.80, both of which are Class C.

IP address, the default subnet mask is 255.255.255.0. After AND operation, the network numbers of the two hosts are the same, indicating that the two hosts are in the same network. 4. Subdivision:

Another function of subnet mask is to divide subnets. In practical application, we often encounter the problem of insufficient number of networks, and it is necessary to divide a certain type of network into multiple subnets. The method adopted is to divide some binary bits in the identification part of the host number to identify the subnet.

Steps:

(1) Converts the number of subnets to the m power of 2. If it is divided into 8 subnets, 8=2 to the third power. If it is 6, take the big one to the third power of 2.

(2) M is converted into decimal after occupying the m bits of the host address in the high order. For example, if M=3 is 1 1 100000, it is converted to decimal 224.

(3) If it is a Class C network, the subnet mask is 255.255.255.224. If it is a Class B network, the subnet mask is 255.255.224.0. If it is a class A network, the subnet mask is 255.224.0.0.

Third, the domain name system and DNS server:

1. Domain name system: Compared with IP addresses, people prefer to use strings with certain meanings to identify devices on the Internet.

Computers, therefore, in the Internet, users can name their computers in many ways, so there may be opportunities to duplicate names on the Internet. For example, the hosts providing WWW services are all called WWW, and the hosts providing E-MAIL services are all called Mail. Therefore, it is impossible to uniquely identify the host location of the Internet. In order to avoid repeated access to the Internet, the Internet Society adopted the method of adding a suffix to the host name. This suffix is called domain name, which is used to identify the regional location of the host. The domain name was legally obtained through application. In this way, hosts on the Internet can be uniquely identified by "host names". Domain name ". For example: WWW.TONGJI.EDIJ.CN, where WWW is the host name, named by EDU.CN, the server administrator.

Is a domain name, which can be legally used by server administrators. Domain names have certain regional affiliation, and the general structure is "regional name, organization name and country name", in which Tongji University stands for Tongji University, EDU stands for national educational institutions and CN stands for China. WWW.TONGJI.EDU.CN represents the WWW host of Tongji University, an educational institution in China.

According to the regulations of Internet Society, there are seven types of organization domain names, namely: COM: commercial organizations. EDU: Organization of educational institutions. INT: international organization. GOV: government organization. MIL: Military organization. NET: network organization. 0RG: Non-profit organization.

Geographical Countries Different countries have different names: China, USA, Japan, France, Australia and Canada.

Canada Britain Britain