What is a computer network?

Two computers connected to the network
A network represents a set of systems connected to one another, who can communicate between them. We say that we are dealing with a computer network if at least 2 computers are connected in such a way as to enable communication and shared use of data between them. There are these types of computer networks:

LAN-Local Area Network
A LAN is distinguished by two basic features: Its geographic extent is limited, and this stretch does not exceed the boundary of the site where the signature is located. All hardware is completely located in the area of ​​jurisdiction and under the supervision of a user, respectively a company. In local networks, data transfer is performed in most cases via cable. The network card manages the transfer of data from the computer to Cable and vice versa. Each network card has a number (address), which is unique and unchanged all over the world and is called MAC address. The MAC address (MAC-Add-on) serves to clearly identify the workstation within the network.

WLAN-Wireless Local Area Network
Wireless Local Area Network is a LAN variant and is distinguished from the latter by the media it uses for data transmission. For data transfer, in this case, radio transmission technology is used instead of cable. For example, one of the standards used recently for data transfer (in an area of ​​about 10 meters) is Bluetooth.

MAN - Metropolitan Area Network
MAN's scope is limited to the area of ​​a city or an industrial center and includes a distance of about 100 km.

WAN - Wide Area Network
The WAN, also called a wide-spread network, is not limited to its geographic extent. In its classical form it served to connect remote computer hardware. The data, in most cases, are transferred to public lines for the use of which there are certain tariffs. Firms can use WAN as a link between their particular LANs.

GAN-Global Area Network
The GAN term describes the extent of a WAN in a global dimension. In a global network the distances between computers that communicate can exceed thousands of kilometers. The data passes their way from the sender to the receiver of many intercepts (routers). The distance is passed not as a whole, but divided into many segments.

The advantages of local networks
 Fast communication;
 Shared use of data and resources;
 Central Administration and Central Data Security ;.
 Common use of software:

The role of special computers in data exchange
In a network, data is exchanged between different computers. When exchanging data, the computers involved in this process assume a special role. Each data exchange is carried out according to the same principle: the client computer sends a request to another computer called the server. Subsequently, the server sends the requested service to the client.

Building a Peer-to-Peer Network
On a Peer-to-Peer network are connected to each other some computers equivalent. Computers have the same rights to each other. They all do the same tasks.

 Every computer primarily serves as a workstation for the employee.
 In addition, any computer can perform certain tasks for another computer.
 Any computer on a Peer-to-Peer network can serve as a server and as a client.
Peer-to-Peer Network

The Peer-to-Peer Network is especially suitable when only a few computers are connected to each other. The network is simply structured and is easily manageable.

Networks with server
For large amounts of data, it is worth to expect a special computer to store shared data and other services. Central data storage on a computer brings the following advantages:

 Data can be backed up without problems at regular intervals.
 Users know exactly where to look for the information they want. Network identification data can be stored on the server. This facilitates user administration.
 The server is centrally controlled for network access rights, user access rights over network resources (eg data and printers), and configuration of security elements.

Types of servers
Depending on the type of service they provide, the servers receive the corresponding names.

 File Server
 Print Server
-Mail Server
 SQL Server
 Web Server
 Domain Controller
 Application-Server etc.