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Computer Networks · Class 12 · Types of Networks
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WAN — Wide Area Network

You put your card into an ATM in Gangtok, and your bank in Mumbai checks your balance before the machine counts out the notes. Two cities more than 1,800 km apart, talking in a second. That takes a WAN.

1What a WAN is

WAN
A Wide Area Network (WAN) connects LANs and MANs spread over a large area — anything from several cities, to a whole state, a country, or countries and continents. There is no limit on its size.
🏙️ cities→🗺️ a state→🇮🇳 a country→🌍 continents

So a WAN does not have to cross an ocean. A bank joining its branches in Gangtok, Namchi and Siliguri, or a state government joining the offices in every district, is already a WAN.

A bank's WAN

Every ring is one branch's LAN. The WAN is what joins them.

Branches in six Indian cities, each with its own LAN, joined to the head office in Mumbai — hundreds of kilometres apart.

2The Internet is the biggest WAN

The Internet joins networks in every country of the world, so it is the largest WAN there is. Remember from the evolution chapter: it is a network of networks — exactly what a WAN is, on the biggest scale.

The biggest WAN — but not the only one
The Internet is the largest WAN, and it is public: anyone with a connection can use it. Many organisations and governments build private WANs of their own — banks, railways, the armed forces, government departments. These are kept separate for security and reliability, and only authorised people can use them.
🌐 Public WAN — the Internet

Open to everyone. Used for websites, email, video calls and online shopping.

🔒 Private WAN

Owned or rented by one organisation, closed to outsiders. A bank’s network joining its branches and ATMs, or a government network joining its offices.

3How a WAN crosses such distances

Nobody lays their own cable from Mumbai to London. A WAN uses links that telephone and internet companies already run:

☎️ Telephone & fibre lines

Long cables between cities, rented from telecom companies.

🌊 Undersea cables

Cables on the ocean floor joining continents.

🛰️ Satellites

For places cables cannot reach — ships, islands, remote areas.

4Features of a WAN

  • Covers a large area — cities, a state, a country, or the whole world.
  • Joins many LANs and MANs.
  • Usually not owned by one organisation; the long links are rented.
  • Costliest to set up, and harder to manage and keep secure.

5Examples

  • The Internet.
  • A bank joining its branches and ATMs across India.
  • Indian Railways’ ticket booking network across the country.
  • A company with offices in many countries.

6Check yourself

Quick Check

Which is the largest WAN?

Quick Check

A state government connects its offices in every district of the state, and only its own staff can use the network. This is…

Quick Check

A company links its offices in Delhi, Dubai and London. What type of network is this?

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🏙️ MAN — Metropolitan Area Network
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