Computer Network consists of group (or number of individual computers) of computer devices which are connected with each other. It allows the computers to communicate each other and share resources which include information, software and peripheral devices such as printers, scanners. A computer network is shown in below figure.

Computer Network

Now days. computers are used in a wider range. All the organizations are using multiple computers within their departments to perform their day to day work. It is necessary to connect them which form a network. The networks are classified into different types according to the network size. When computers communicate with each other, they follow certain specific formats and rules. These formats and rules are defined by the OSI (Open Systems Interconnection) model. The OSI model is conceptual and has seven layers and each layer is having its own functions.

A network selection criterion forms the networking basics, since it helps to select a secure and efficient network. The criterion explains network performance improvement techniques and necessity of reliable network. Various standards organizations are used for network communication to maintain consistency.

Need for Computer Networks:

Computer Network consists of group (or number of individual computer) of computers and devices which are connected with each other. Thus, when these computers are in the network it helps users to share the resources and communicate with each other. Computer Networks can be used for many purposes:
1. sharing Files, folders, data and information.
2. Sharing hardware resources such as a network printer.
3. sharing software, as many users connected to the network can run the same Application program.

Computer networks hardware

Computer network allows the user to share data with other users in a network, for example, a company having a number of computers which are connected in a network. Computer network will enable the users to share files and folders and get synchronized other users.

Computer Network also allow the user to share resources as printers and faxes. Printers can be installed on one computer and can be accessed by other user in a network. By this, the need of installing printers on individuals computers is avoided and it results in cost-effectiveness. Computer network also allows the user to communicate with each other using instant messaging tools to share ideas, files or solve queries.

The user can also set up a central system wherein common files and folders which are frequently used by the users can be stored. All the users within the network can easily access those files. Instead of taking backups from individuals computer, the user data backup can be scheduled and stored on a central system. This helps in reducing the time of taking backup.

If an Organization you have several computers but just one dial up connection, a network makes it easier to use the Internet. Several computers can share one modem to use the same Internet connection. Otherwise, you can even install a dedicated high-speed Internet connection such as a cable modem for your network security.

It is possible to add new systems or servers to an existing network easily. Thus the computer hardware network provides scalability. It is also reliable to use a network as it uses redundancy.

There are two types of network configuration:
1. Client-Server model.
2. Peer-to-Peer Model.

Client Server Model:

Client/server is a configuration of the computer network that includes a server and one or more clients. The clients manages the local resources that are used by the user such as monitor, keyboard, CPU and Peripherals. The server is a more powerful system which manages shared resources such as database, printers, communication Links or high powered-processors and handles all the incoming requests for all its shared resources.


Server is a centralized and dedicated entity which manages data, printers or network traffic depending upon the type of the server. The server must run a server program to share its resources. In a network, one server can be used for multiple purposes or you can have multiple servers for a specific application. Many programs are built into the operating system which can be used for the sharing of resources and for other purposes.

Client is a computer on which user runs application. Clients can also be called as workstations. The network resources are stored on the server and are accessed by the clients. Clients-Server architecture is also known as two-tier architecture. The example of this type network is Novell Network client/server system.

Server-Client model

Peer-to-Peer Model:

Peer-to-Peer is a communication model in which each party has the same capabilities and either party can initiate a communication session. Peer-to-Peer communications is Implemented by giving each communication node both server and clients capabilities. In recent usage, Peer-to-peer has come to describe applications in which users can use the Internet to exchange files with each other directly.

peer-to-peer connection

I hope this blog post may be helpful for you and click here for full Security Guide to Computer Network Security 3rd Edition [2015]