Computer Networks & Types & Functions

 

Computer Networks

A computer network is a system where two or more computers are connected to share data, resources, and communication services like files, printers, internet, etc.

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1.2.1 Basic Definition & Types

Basic Definition:

A network allows computers to “talk” to each other using wired or wireless connections.

Main Types of Networks:

Networks are mainly divided into two categories:

1. Physical (Geographical) Networks
2. Virtual (Logical) Networks

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1.2.2 Geographical Area Wise (Physical Networks)

These networks are classified based on distance coverage.

1. LAN (Local Area Network)

• Covers small area like:
  • Room
  • Office
  • School / Lab
• High speed network
• Example: Computer lab network in your college

👉 Simple idea: Small area, fast connection

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2. MAN (Metropolitan Area Network)

• Covers a city or large campus
• Connects multiple LANs
• Example:
  • University campuses across a city
  • City government networks

👉 Medium range network (city level)

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3. WAN (Wide Area Network)

• Covers large distances (countries / continents)
• Uses public and private communication lines
• Example:
  • Banking systems
  • Mobile networks
  • Internet backbone

👉 Very large network

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4. Internet

• The largest WAN in the world
• Global network of networks
• Connects billions of devices worldwide

👉 Example: Google, YouTube, WhatsApp all work through internet

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1.3 Virtual (Logical Networks)

Virtual networks are not physical — they are created using software.

They help in security, management, and organization of networks.

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1.3.1 VLANs (Virtual Local Area Networks)

A VLAN divides one physical network into multiple logical networks.

Example:

In a school:

• Admin department network
• Teachers network
• Students network

All use same cables but are separated logically.

Benefits:

• Better security
• Reduced traffic
• Easy management

👉 Simple idea: One network, but divided into groups

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1.3.2 VPNs (Virtual Private Networks)

A VPN creates a secure connection over the internet.

How it works:

It hides your real location and encrypts your data.

Example:

• Employees working from home connecting to office network securely

Benefits:

• Data security (encryption)
• Privacy
• Remote access

👉 Simple idea: Secure tunnel over internet

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1.4 Function / Working of Computer Network

A computer network works through these basic steps:

1. Data Sharing

• Computers send and receive data

2. Communication

• Devices communicate using protocols (rules)

3. Resource Sharing

• Printers, files, internet shared among users

4. Data Transmission

• Data is broken into small packets
• Sent through cables or wireless signals
• Reassembled at destination

5. Network Devices Role

• Router → directs data
• Switch → connects devices in LAN
• Modem → connects to internet