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Informatics Practices · Class 12 Optional

Ch 5Internet and Web — Class 12 Informatics Practices, concept-first.

We live in a connected world. Information is produced, exchanged, and tracked across the globe in real time. This is possible because almost everyone and everything in the digital world is interconnected in some way.

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Q&A

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Concepts

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Key concepts

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Real World Networks

Think about the last time you called a friend, sent a WhatsApp message, or even just walked into a crowded room. In each case, you were part of a network — a structure of connections.

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Chapter contents

The NCERT structure, section by section. Open a section to see its questions, then read the concept-first solution.

5.1

Introduction to Computer Networks

2 Q

We live in a connected world. Information is produced, exchanged, and tracked across the globe in real time.

5.2

Types of Networks

A computer network is not a single, uniform thing. The network inside your school computer lab is very different from the network that connects a bank's branches across the country.

5.2.1

Local Area Network (LAN)

A Local Area Network is a network that connects devices kept within a limited physical distance. The key idea is short range — a LAN does not stretch across cities or countries.

5.2.2

Metropolitan Area Network (MAN)

A Metropolitan Area Network, or MAN, is a natural step up from a Local Area Network. While a LAN covers a single building or campus, a MAN extends that reach to cover an entire city or a large town.

5.2.3

Wide Area Network (WAN)

A Wide Area Network (WAN) is a network that spans a very large geographical area — much larger than a LAN or a MAN.

5.3

Network Devices

A network is only as useful as the devices that connect it. Without the right hardware, data cannot travel from one computer to another, nor can it cross from one network to a different one.

5.3.1

Modem

A modem — short for MOdulator-DEModulator — is the device that makes it possible for computers to send and receive data over telephone lines or other analog transmission media.

5.3.2

Ethernet Card

An Ethernet card is the hardware that physically connects a computer to a wired network. It is also called a Network Interface Card (NIC) or a network adapter.

5.3.3

Repeater

A repeater is a device that solves a simple physical problem: signals weaken as they travel along a cable. After a certain distance, the signal becomes too weak to be reliably interpreted.

5.3.4

Hub

An Ethernet hub is a simple network device that connects multiple devices — like computers or printers — using wired cables.

5.3.5

Switch

A switch is a networking device that acts as the central connection point in a Local Area Network (LAN).

5.3.6

Router

A router is a network device that does more than just forward data — it examines the data it receives, decides how to handle it, and can send it across different types of networks.

5.3.7

Gateway

A gateway is exactly what its name suggests — a “gate” between an organisation’s internal network and the outside world of the Internet.

5.4

Networking Topologies

A network is more than just a collection of wires and devices — the way those devices are arranged matters a great deal. That arrangement is called the topology of the network.

5.4.1

Mesh Topology

In a mesh topology, every device in the network is directly connected to every other device. This creates a web of point-to-point links, as shown in Figure 5.12 of the textbook.

5.4.2

Ring Topology

In a ring topology, each node (computer or device) is connected to exactly two other nodes — one on its left and one on its right. This creates a closed loop, or ring, of connected devices.

5.4.3

Bus Topology

In bus topology, every device on the network connects to a single, shared communication line. That central cable is called the bus (or backbone).

5.4.4

Star Topology

In a star topology, every device on the network is connected directly to a central node. That central node is a networking device — typically a hub or a switch.

5.4.5

Tree or Hybrid Topology

A network topology is the physical or logical arrangement of devices in a network. A tree topology (also called a hybrid topology) is a hierarchical structure where a central backbone connects multipl…

5.5

The Internet

The Internet is not just a collection of computers. It is the global network of computing devices — desktops, laptops, servers, tablets, mobile phones, and handheld devices — along with peripheral dev…

5.6

Applications of Internet

The Internet is not a single service — it is a platform that enables many different kinds of communication and information sharing.

5.6.1

The World Wide Web (WWW)

The World Wide Web — often called the web — is a vast ocean of information stored as trillions of interlinked web pages and other resources.

5.6.2

Electronic Mail (Email)

Email, short for electronic mail, is a method of sending and receiving messages over the Internet. Unlike a phone call, an email does not require the recipient to be online at the same time you send i…

5.6.3

Chat

Chatting, also called Instant Messaging (IM), is a way to communicate with people in different geographic locations in real time using text messages.

5.6.4

VoIP

Voice over Internet Protocol, or VoIP, allows voice calls (telephone service) to be made over the Internet rather than through the regular telephone network.

5.7

Website

A website is something you have almost certainly used — but what exactly is it, technically? At its simplest, a website is a collection of web pages that are linked together and stored on a web server…

5.7.1

Purpose of a Website

We are living in an Internet era where the whole world is connected. A website’s fundamental purpose is to make information available to people at large.

5.8

Web Page

A web page is a document on the World Wide Web that you view inside a web browser. Every page you open — whether it shows text, images, or a video — is a web page.

5.8.1

Static and Dynamic Web Pages

A web page is not always the same for every visitor. Whether its content stays fixed or changes based on who is viewing it depends on whether the page is static or dynamic.

5.9

Web Server

A web server is the foundation of every website you visit. It is the system that stores a website's files and delivers them to a user's browser when requested.

5.10

Hosting of a Website

Web hosting is the service that makes a website or web page available on the Internet, turning it into a part of the World Wide Web.

5.10.1

How to host a website?

To host a website, you need to make your website's files available on a computer that is always connected to the internet — a web server.

5.11

Browser

A browser is a software application whose job is to fetch and display web pages. When you type a web address or click a link, the browser contacts the web server, retrieves the requested data, and ren…

5.11.1

Browser Settings

Every web browser has a set of built-in settings that control how it behaves. These settings cover areas like privacy, which search engine to use, how downloads are handled, autofill and autocomplete…

5.11.2

Add-Ons and Plug-ins

Add-ons and plug-ins are tools that extend and modify the functionality of a browser. Both boost browser performance, but they are fundamentally different from each other.

5.11.3

Cookies

A cookie is a small text file — a simple string of information — that a website transfers to your browser when you visit it. This file gets stored on your computer by the browser itself.

Summary

- A group of two or more similar things or people interconnected with each other is called a network. - A computer network is an interconnection among two or more computers to share data and resources…

Exercises

+Show 17 questions17 questions
  1. Q1Fill in the blanks: (a) To transmit data for sharing on a network, it has to be divided into smaller chunks called ______________________. (…Free
  2. Q2Expand the following: (a) ARPANET (b) ISP (c) URLFree
  3. Q3Name the device for the following: (a) It stands for Modulator Demodulator (b) It regenerates the signals.Free
  4. Q4Differentiate between: (a) MAN and WAN (b) Website and web page (c) Router and Gateway (d) Bus and Star topology (e) Static and Dynamic web…Preview
  5. Q5Define a network. What is the need of forming a network?Preview
  6. Q6Give any two examples of networks.Preview
  7. Q7Give any three applications on the Internet.Preview
  8. Q8Name any two mail service providers.Preview
  9. Q9Explain VoIP.Preview
  10. Q10What is DNS?Preview
  11. Q11Identify the type of topology from the following: (a) Each node is connected with the help of a single cable. (b) Each node is connected wit…Preview
  12. Q12Sahil, a Class X student, has just started understanding the basics of Internet and web technologies. He is a bit confused in between the te…Preview
  13. Q13Murugan wants to send a report on his trip to the North East to his mentor. The report contains images and videos. How can he accomplish his…Preview
  14. Q14Mampi is planning to open a company that deals with rural handicrafts. She wants to advertise about handicrafts on a social platform. Which…Preview
  15. Q15Ruhani wants to edit some privacy settings of her browser. How can she accomplish her task?Preview
  16. Q16Shubham wants to play a video in his browser but he is not able to do so. A message on the screen instructs him to install the Adobe Flash P…Preview
  17. Q17When Joe typed a URL in the address bar of his browser, Error 404 was displayed? Why did this happen? What can be done to avoid it?Preview

CBSE Sample Papers

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