Computer Networks
Class 12 · Computer Science
4 ideas in Class 12 Computer Science, explained in plain words, with games and quizzes to practise.
What a Network Is
Part of: Networks and their reach
A computer network links two or more computing devices so they share data and resources like files and printers. Each communicating device is a node, from phones and laptops to servers and printers. Data travels in small chunks called packets over wired cables or wireless air.
Why it matters. Sharing and instant messaging all rest on networks. Learners who grasp nodes and packets understand every app that sends or fetches.
Key words
- Network
- : Linked devices sharing data and resources.
- Node
- : One communicating device in a network.
- Packet
- : A small chunk of data carried across.
- Resource Sharing
- : Many computers using one printer or store.
Try it in two minutes
- Name three connected devices at home.
- Share one printer between two of them.
- Ask what small chunks carry a photo across.
Try at home. Ask your child to map every connected device in one room.
Types of Networks
Part of: Networks and their reach
Networks are grouped by reach. A personal network spans about ten metres around one person. A local network covers a room, floor or campus up to about one kilometre at high speeds. A city network spans a town up to tens of kilometres, often joining local ones. A wide network crosses countries and continents, and the Internet is the largest of them.
Why it matters. Reach decides cost, speed and safety. Learners who match each network to its span choose correctly for homes, campuses, cities and the globe.
Key words
- PAN
- : A personal network spanning about ten metres.
- LAN
- : A fast local network for rooms and campuses.
- MAN
- : A city network joining local networks.
- WAN
- : A wide network crossing regions and countries.
Try it in two minutes
- List the devices within ten metres of you.
- List the devices across your school campus.
- Ask which network fits each list.
Try at home. Ask your child to label home, school and city networks with their types.
Devices and Topologies
Part of: Building and naming the net
Devices shape traffic: the modem swaps digital bits with line signals, the hub shouts to all lines, the switch forwards to the addressed device only, the repeater rebuilds weak signals, the router joins different networks, and the gateway guards entry and exit. Layouts shape wiring: mesh links every pair, ring chains neighbours one way, bus shares one backbone, star meets at a centre, and tree mixes branches.
Why it matters. Right devices cut collisions and right layouts survive failures. Learners who match each job to its device and layout build fast, sturdy networks.
Key words
- Modem
- : Swapping digital bits with line signals.
- Switch
- : Forwarding each packet only to its address.
- Router
- : Joining different networks and picking paths.
- Gateway
- : The guarded entry and exit of a network.
- Topology
- : The wiring layout of a network.
Try it in two minutes
- Connect four toy phones with strings in a star.
- Break one string and ask what still works.
- Rewire as a ring and compare.
Try at home. Ask your child to draw home Wi-Fi as a star with the router at the centre.
Addressing Web and DNS
Part of: Building and naming the net
Every network card carries a permanent 48-bit hardware address written as twelve hex digits. Internet addresses identify nodes: the older 32-bit form shows four numbers from zero to 255, while the newer 128-bit form shows eight hex groups. The web is the ocean of linked pages built with page language, addresses and transfer rules. Domain names replace hard numbers, and DNS servers translate each name to its address.
Why it matters. Addresses route every message and names keep them human. Learners who read both forms and resolve names understand how a click becomes a connection.
Key words
- MAC Address
- : The permanent hardware address of a network card.
- IP Address
- : The network address locating a node.
- Web
- : The linked pages and resources over the Internet.
- DNS
- : The system translating names to addresses.
Try it in two minutes
- Read a device hardware address together.
- Split a four-part Internet address into its parts.
- Type a domain name and ask who finds its numbers.
Try at home. Ask your child to explain why names beat raw numbers for websites.
What your child will practise
- Addressing Web and DNS: Ocean Puzzle (Clue Puzzle)
- Devices and Topologies: Ocean Quick Fire (Quick Fire)
- Types of Networks: Jungle Quick Fire (Quick Fire)
- What a Network Is: Candy Quick Fire (Quick Fire)
- What a Network Is: Desert Puzzle (Clue Puzzle)
- Quiz: Addressing Web and DNS (8 questions)
- Quiz: Devices and Topologies (8 questions)
- Quiz: Types of Networks (8 questions)
- Quiz: What a Network Is (8 questions)