Touchpad Plus Ver. 3.1 Class 8: Linux & LibreOffice

1 COMPUTER NETWORKING

The process of connecting computers and peripheral devices with each other, so that they can exchange data is called computer networking. Various hardware devices, protocols and software are required for networking. In this chapter you are going learn about networking and the concepts related to computer networking.

COMPUTER NETWORK

A computer network is a group of interconnected computer systems and other computing devices.

The computers on the network can communicate with each other as well as work independently. Each computer in a network is called a node. The computers in the network maybe linked through a cable, hub, switch, NIC (Network Interface Card), modem or router.

There are different kinds of computer networks that work in different ways. Networks may be very small and simple or they may be complex as a global network like the Internet. There may be wired or wireless connection between computers on the network.

NEED FOR COMPUTER NETWORK

Computers and other devices connected on a network help in:

Resource Sharing: It help the users to share files and hardware devices such as printers, scanners, etc.

Communication: It helps us to communicate with others through e-mail, video conference, instant messaging, etc.

ADVANTAGES OF COMPUTER NETWORK

The advantages of computer network are:

The information can be easily shared by people.

It reduces the cost of hardware.

Store information in one centralised location.

Reliability implies backing up of information. If a system crashes, then the information is accessible on another workstation for future use.

Reduction in installation cost.

User authentication process to secure the data.

People will have access to all the information they need to get and share through e-mails and instant messaging which saves time and money in passing information.

COMPONENTS OF A NETWORK

There are mainly five components of a network which are as follows:

Sender: A sender is a computer that wants to send information to other computer connected to the network.

Receiver: A receiver is a computer which is expecting the data from other computer on the network.

Transmission Medium: A transmission medium is a communication channel through which information is transferred from one computer to another on a network.

Message: A message is the information or data which needs to be transferred from one computer to another.

Protocol: A protocol is set of standard rules used for communication.

NETWORK TERMINOLOGIES

There are several terms related to computer network. Let us discuss some of them.

Server

A server is also called host computer. It controls the access to the hardware and software on the network. It provides a centralised storage area for the programs, data and information.

The computer which performs a specific task is called a dedicated server.

The computer which manages the printers and documents being printed is called the print server.

The computer which stores and provides the access to a database is called a database server.

The server which manages the network traffic is called a network server.

The computer which delivers the requested web pages to our computer is called a web server.

Client

It is a computer which depends on the server for all the resources. For example, a server might store a network version of Excel program. Every client on the network can access the Excel program from the server.

Internet

Internet is a global network of millions of computers and computer networks all over the world. It allows us to access and share information over the network. The Internet contains billions of web sites to provide information.

Intranet

A computer network that is used for sharing information, devices and other computing services only within an organisation is called Intranet.

URL

It stands for Uniform Resource Locator. It is the address of a website, such as www.google.com, www.rediffmail.com.

ISP

It stands for Internet Service Provider. It is a company that provides Internet access on payment of a monthly fee. Some of the ISPs are Airtel, Vodafone, BSNL, (Bharat Sanchar Nigam Limited), MTNL (Mahanagar Telephone Nigam Limited.), Jio, etc.

IP Address

An Internet Protocol (IP) address is an unique identification number assigned to a computer connected to a network. It has two main functions: host or network interface identification and location addressing. IP addresses are written and displayed in human-readable notations, such as 172.16.254.1.

DNS

Domain Name System (DNS) is a naming system for assigning a name to the computers, services, or other resources connected to the network. This name is known as domain name. For example, the domain name in the www.yahoo.co.in URL is yahoo.co.in. This domain name is internally converted into IP address.

Web Page

A single digital page on the World Wide Web (WWW) that contains information and links of another pages is called a web page. Web pages are created by using the Hyper Text Markup Language (HTML).

Website

A website is a collection of web pages which are interlinked to each other. A website may contains thousands of web pages.

Web Portal

A website that is specifically designed to provide a single point of access for information is called web portal. Web portals are also known simply as portals. The major difference between a website and a web portal is that a portal works as a gateway to WWW and provides several services. On the other hand, a website may provides only some limited services.

Hypertext

The text that has a special feature of connecting one web page to another is called a hypertext.

Link

A link can be defined as a web address that is used to make connectivity between web pages.

Hyperlink

A hyperlink is simply a part of the Web page that is linked to a URL. A hyperlink can appear as text, an image, or a navigational tool such as a button or an arrow. When you click on a hyperlink, you will jump to the URL specified by the hyperlink. Hyperlinked text usually looks different from normal text in a Web page. It is often underlined, but can be formatted in a number of ways.

Bandwidth

The capability of a transmission medium to transmit the maximum amount of data from one computer to another over a computer network in a given amount of time is called bandwidth. A bandwidth is generally in bits per second (bps) or Bytes per second (Bps), Kilobytes per second (Kbps) and Megabytes per second (Mbps). There can be various types of bandwidths which are network bandwidth, data bandwidth, or digital bandwidth.

EVICES REQUIRED FOR A NETWORK

There are various types of devices such as Network Interface Card (NIC), Hub, Switch, Router, Modem and Network Cable. Let us discuss about these in detail.

Network Interface Card (NIC)

It is an expansion card which provides the network access to a computer.

It allows the computer to connect to a network through a wired or wireless medium.

Hub or Switch

It is hardware device that has various boxes to which the computers, printers and other networking devices are connected. The main function of a hub is to direct information around the network and facilitate communication between all the connected devices.

Router

It is a networking device used to connect and facilitate transfer of data in the form of packets between two network. It finds best route for data packets over the network. It is located at the gateways where two networks connect.

Modem

It stands for MODULATOR-DEMODULATOR. It is a hardware device that is used to connect a computer to the Internet via a telephone line or a wireless medium. It converts data from digital to analog and vice versa. The process of converting analog signals to digital signals is called modulation. The process of converting digital signals to analog signals is called demodulation.

Networking Cable

Networking cable, also known as Ethernet cable is a transmission medium that allows to transport information from one place to other place. There are various types of networking cables such as coaxial cable, twisted pair cable, and optical fiber cable.

Gateway

A gateway is a network device that allows the data to flow between two different networks which may use different protocols. It collects data that is to be sent from one computer, converts it into small packets and then sends them to another computer.

TYPES OF NETWORKS

Different types of networks can classified on the basis of geographical areas covered. There are five types of networks as follows:

LAN (Local Area Network)

LAN is a short form of Local Area Network. It is a digital communication system that interconnects a larger number of computers and other peripheral devices within a radius of less than 1 km. This type of network is usually preferred for a smaller area such as a residence, school, laboratory, university campus or office building. By using the LAN network, users can exchange data and messages in the easy and fast way. Cables and communication devices are used to connect computers to the LAN.

MAN (Metropolitan Area Network)

This network consists of two or more local area networks together that usually spans several buildings in the same city or town.

WAN (Wide Area Network)

It is a digital communication system that interconnects a large number of computers in a wide geographical area. This network may operate on a worldwide or nationwide basis. In such type of network, there may not be physical connection between computers. In WAN telephone lines, microwave, satellite links, etc.; can be used as transmission medium.

PAN (Personal Area Network)

These are privately owned networks. PAN is used to establish the communication amongst the computers within the range of 20 to 30 feet. It can be wired or wireless.

CAN (Campus Area Network)

CAN, also known as Cluster Area Network connects two or more LANs that are limited to specific geographical areas, for example, college campus, office building etc. A campus area network is larger than LAN since it may span in multiple buildings within a specified area.

TOPOLOGY

Topology refers to the geometric arrangement of computers or nodes in a network. The factors that determine the type of topology are cost, flexibility and reliability. There are five different types of topologies. Let us learn about these in detail.

Bus Topology