What is Network?
Definition: A computer network is a group of computers that are connected together to communicate and share resources such as files, printers, and email. Networks include network media, such as a cable, to carry network data; network adapter hardware to translate the data between the computer and the network media; a network operating system to enable the computer to recognize the network; and a network protocol to control the network communication.
There are three primary network models, which are design specification for how the computers and other nodes on a network can interact.
Centralized: A centralized network is a network in which a central host computer controls all network communication and performs data processing and storage on behalf of clients. Users connect to the host via dedicated terminals or terminal emulators. The terminals have few or no local computing resources of their own. Centralized networks provide high performance and centralized management, but they are also expensive to implement. Centralized networks are also called “hierarchical networks” and “host-based networks”.
Client-server: A client/server network is a network in which computer functionality is divided into two rules: server computers, which provide services and control network operation, and client computers, which use services and conform to network management and security requirements. Typically, there is at least one server providing central authentication services. Servers also provide access to shared files, printers, hardware, and applications. In client/server networks, processing power, management services, and administrative functions can be concentrated where needed, while clients can still perform many basic end-user tasks on their own.
Peer-to-peer: A peer-to peer network, sometimes called a workgroup, is a network in which resource sharing, processing, and communications control are completely decentralized. All clients on the network are equal in terms of providing and using resources, and users are authenticated by each individual workstation. Peer-to-peer networks are easy and inexpensive to implement. However, they are only practical in very simple organizations, due to the lack of central data storage and administration. In a peer-to-peer network, user accounts must be duplicated on every workstation form which a user accesses resources. Such distribution of user information makes maintaining peer-to-peer networks difficult, especially as the network grows.