A network is a number of computers connected together to share information and hardware. The purpose of a network is to enable the sharing of files and information between multiple systems. The internet could be described as a global network of networks. Computer network can be connected through cables such as ether cables (phone lines) (or) wirelessly, using wireless networking cards (or data cards) that sends and receives data through the air. A network is actually a system which can consist of many things such as the computer and peripherals, specific networking cards within each computer and peripheral, the cables and communication lines which link all the computers and peripherals together, central hardware devices which connect computer and route data to the right places on the network (hubs, patch panels, routers)., network operating system software, networking software in each computer and peripheral that lets them talk [communicate] to each other, an ADDRESS system to identify each part of the network to all the other parts and often, a main computer usually called servers (or) Hosts.

Hosts: A computer which mediates multiple accesses to data bases mounted on it’s (or) provides other services to a network. A host is a node in a network. In a network a node is a connection point, either a distribution point (or) an end point for data transmission. In general a node has programmed (or) engineering capability to recognize and process (or) forward transmission to other nodes.

Lan Man Wan Intranet Extranet Hybrid Networks

There are specially 6 kinds of networks are there. They are listed below

  •   LAN [Local Area Network]
  •   MAN [Metropolitan Area Network]
  •   WAN [Wide Area Network]
  •   Intranet
  •   Extranet and
  •   Hybrid network


LANs are privately owned networks which are embedded within a campus, single building (or) within an organization up to few kilometers in size.  They are mainly used to share the resources like printers, scanners between personal computers in a campus, factories and offices and they exchange information too. They are restricted in size that is the transmission [transmission means the conveyance of information from one space to another.] of information time is bounded and known in advance. It simplifies network management. Traditional LAN uses a transmission technology which contains a cable to which all the systems are connected or attached. They run at a speed of 10Mbps to 100mbps and they have very low delay [microseconds (or) nano seconds] and may make few errors. Latest LANs have the capacity to operate and run at a speed of up to 10Gbps. 


MAN covers a city. The best known example of a MAN is the cable television network available in many cities. This technology grew from earlier community antenna systems used in areas with poor over-the-air television reception. In these early systems, a large antenna was placed on top of a nearby hill and signal was then piped to the subscriber’s houses. At first these were locally designed ad-hoc systems. Then, companies began jumping in to the business, getting contracts from the city governments to wire up an entire city. After this the television programming will be done and entire channels would be designed for cables only. Most of the channels were highly specialized such as all news, all sports, all cooking, all gardening, and so on. Now days we can see many digital channels. In this tele- programming the subscribers has the provision to select their own channels and can pay only for them. One picture quality varies from one cable to another. Cable television is not the only MAN.  



             WAN covers a large geographical area of a country (or) a continent. It contains a collection of hosts intended for running user application programs. The hosts are connected by a communication subnet. The task of the subnet is to carry messages from host to host. The other side the host is actually owned by the customers. The subnet is operated by an internet service provider. WAN consists of two distinct components namely Transmission lines and switching elements. In transmission lines they move between bits machines and are made of copper wire, optical fiber or even radio links. Switching elements are specialized computers that connect multiple transmission lines. When data arrives on an incoming line, the switching element will choose an outgoing line on which to forward them. These switching computers are called as routers.


        Intranet is a communication environment created within an organization using internet technology. It is an external website that utilizes the internet technology such as protocols [protocols are nothing but a set of rules for communication that define how a particular task is to be done.] for efficient internal communication. It uses TCP/IP [Transmission Control Protocol and Internet Protocol] network technologies besides internet resources such as WWW, e-mail, Telnet and FTP [File Transfer Protocol]. But the network is not open to people outside the organization or company. The intranet is separated from the internet using a firewall from outside the company. Intranet allows electronic collaboration between people in the company. Groupware Technologies are employed to support online Brain Storming [Brain Storming means members in the company gather to solve a specific issue and the group used few creative techniques. They contribute few ideas for solving an issue], group meetings and other kinds of collaborative work. It also facilitates video conferencing between people in various parts of the country (or) world. The most important benefit of intranet is its quick access of published documents. It is very useful when large amount of constantly changing [dynamic] information has to be communicated simultaneously to a large number of people within an organization. 


           When an organization extends access to its intranet resources to its business partners, like suppliers and customers, the intranet becomes an extranet. External organizations are provided access to information relevant for them. They are used as project management tools for companies and collaborating third parties, sharing proprietary ideas with a selected group, online training for resellers, it uses high volumes of data using EDI [electronic Data Interchange], it is still used in collaborating with other companies on joint development efforts and shares information of common interest exclusively with partner companies.


         In most cases instead of a single topology [the layout of the computers that are physically connected to a network], a combination of topologies may be used for greater flexibility and reliability. Hybrid network combines features of star, ring and bus network.