Computer Network

COMPUTER NETWORKS Computer Network: A computer network is a system of interconnected computers and peripheral devices. Usually, the connections between computers in a network are made using physical wires or cables. However, some connections are wireless, using radio waves or infrared signals. For example, it may connect computers, printers, scanners and cameras. The generic term node or host refers to any device on a network. Data transfer rate The speed with which data is moved from one place on a network to another. Data transfer rate is a key issue in computer networks Client Server Model: Computer networks have opened up an entire frontier in the world of computing called the client/server model

File server a computer that stores and manages files for multiple users on a network. Web server is a computer dedicated to responding to requests (from the browser client) for web pages.

Communications: Communications is about the transfer of information from a sender, across a distance, to a receiver. Communication is an act of transmitting messages. Types of Networks:  Local-area network (LAN)  Wide-area network (WAN) 

Metropolitan-area network (MAN)

Local-area network (LAN):

Local Area Network Smallest network compared to the other two networks. The simplest form of LAN is to connect two computers together. LAN is operated within a limited physical area, such as at home, school, a single building or several buildings. A network which consists of less than 500 interconnected devices across several buildings, is still recognised as a LAN.

Wide-area network (WAN): The largest network of all network types. Internet is the largest WAN in the world. WAN generally covers large distances such as states, countries or continents. Eg: Local banks have always maintained their business online by connecting all computers of their branches in the countries. International banks also use WAN to connect their computers all over the world. WAN is a group of MANs or LANs or the mixture of both networks.

Wide-area network (WAN)

Metropolitan-area network (MAN): ‘Metropolitan' - describes important cities like New Delhi, Mumbai, Kolkata, bangaluru, Chennai etc. Companies that have several branches within the Mumbai city such as banks, use a MAN. Can be a collection of several LANs within the same city. MAN can be defined as a group of computers and network devices connected together within a large physical area.

Metropolitan-area network (MAN)

Comparison of LAN, MAN, WAN:

Network Architecture: Overall design of a computer network that describes how a computer network is configured and what strategies are being used. Mainly focuses on the functions of the networks. CLIENT/SERVER NETWORK: A client/server network is a network in which the shared files and applications are stored in the server but network users (clients) can still store files on their individual PCs. A server is a computer that shares information and resources with other computers on a network. A client is a computer which requests services or files from a server computer. Peer-to-peer or P2P: It is a network with all the nodes acting as both servers and clients. A PC can access files located on another PC and can also provide files to other PCs. All computers in the peer-to-peer network has equal responsibilities and capabilities to use the resources available on the network. With peer-to-peer network, no server is needed; each computer in the network is called a peer.

Difference:

Network Protocols : Network protocols are layered such that each one relies on the protocols that underlie it. Sometimes referred to as a protocol stack

TCP/IP: TCP stands for Transmission Control Protocol. TCP software breaks messages into packets, hands them off to the IP software for delivery, and then orders and reassembles the packets at their destination. IP stands for Internet Protocol. IP software deals with the routing of packets through the maze of interconnected networks to their final destination.

High-Level Protocols: – File Transfer Protocol (FTP) – Telnet – Hyper Text Transfer Protocol (http) – Simple Mail Transfer Protocol (SMTP) Firewalls: Firewall A machine and its software that serve as a special gateway to a network, protecting it from inappropriate access/ Filters the network traffic that comes in, checking the validity of the messages as much as possible and perhaps denying some messages altogether. Enforces an organization’s access control policy.

Applications of Computer Networks:  File sharing.  Printer sharing.  Communication and collaboration.  Remote access.  Data protection. 

Centralized Support and Administration.

REFERENCE: – Basic Computer Application by: Vishal khasgiwala & Sumitra Jain – Search results from Google.