Types of Networks, LAN, WAN, MAN, CBSE Computer Science

Computer networks connect devices to share resources and communicate. Understanding different types of networks, topologies, and devices is essential for CBSE Computer Science exams across Classes 9-12. This guide covers everything you need to know.

What is a Computer Network?

A computer network is a group of two or more computers connected together to share data, resources, and communicate with each other.

Why do we need networks?

1. Resource sharing - Share printers, scanners, Internet
2. Data sharing - Share files between computers
3. Communication - Email, messaging, video calls
4. Centralized management - Manage all computers from one place
5. Cost saving - Share expensive resources instead of buying for each computer

Types of Networks by Size

1. PAN (Personal Area Network)

A PAN covers a very small area, typically around one person (about 10 meters).

Feature	Detail
Area	Around one person (up to 10 meters)
Devices	Phone, laptop, Bluetooth earphones, smartwatch
Technology	Bluetooth, USB, Infrared
Speed	Low to moderate
Example	Connecting your phone to Bluetooth earphones

2. LAN (Local Area Network)

A LAN connects computers within a small area like a room, building, or campus.

Feature	Detail
Area	Small area (up to 1-2 km), room, building, campus
Ownership	Usually owned by a single organization
Speed	High (100 Mbps to 10 Gbps)
Technology	Ethernet, Wi-Fi
Cost	Low setup and maintenance
Error Rate	Very low
Examples	School computer lab, office network, home Wi-Fi

3. MAN (Metropolitan Area Network)

A MAN covers a city or large town, connecting multiple LANs.

Feature	Detail
Area	City or town (up to 50-100 km)
Ownership	Can be owned by one or multiple organizations
Speed	Moderate to high
Technology	Fiber optic, cable
Cost	Moderate
Examples	Cable TV network in a city, university campuses across a city

4. WAN (Wide Area Network)

A WAN covers a large geographical area, countries or even the entire world.

Feature	Detail
Area	Country, continent, or worldwide
Ownership	Operated by ISPs and telecom companies
Speed	Lower than LAN (varies widely)
Technology	Fiber optic, satellite, telephone lines
Cost	High
Error Rate	Higher than LAN
Examples	The Internet, banking networks

Comparison Table

Feature	PAN	LAN	MAN	WAN
Full Form	Personal Area Network	Local Area Network	Metropolitan Area Network	Wide Area Network
Area	~10 m	Up to 1-2 km	Up to 100 km	Unlimited
Speed	Low	Very high	High	Variable
Ownership	Individual	Single organization	One or more orgs	ISPs, telecom
Cost	Very low	Low	Moderate	High
Error rate	Very low	Low	Moderate	Higher
Example	Bluetooth devices	School lab	City cable network	Internet

Exam tip: This comparison table is a very common question. Remember the order of size: PAN < LAN < MAN < WAN.

Network Topologies

A network topology is the arrangement or layout of devices in a network. It describes how computers and other devices are connected.

1. Bus Topology

All devices are connected to a single cable (called the backbone or bus).

Advantages:

• Easy to set up, Low cost (uses less cable), Good for small networks

Disadvantages:

• If the main cable fails, the entire network goes down, Difficult to troubleshoot, Performance decreases as more devices are added, Limited cable length

2. Star Topology

All devices are connected to a central device (usually a switch or hub).

Advantages:

• If one cable fails, only that device is affected, Easy to add or remove devices, Easy to troubleshoot, Good performance

Disadvantages:

• If the central device fails, the entire network goes down, Uses more cable than bus topology, Central device can be expensive

This is the most commonly used topology in modern networks.

3. Ring Topology

Devices are connected in a circle. Data travels in one direction (or both in a dual ring).

Advantages:

• Equal access for all devices, Performs well under heavy load, No need for a central device

Disadvantages:

• If one device or cable fails, the entire network fails, Adding or removing devices disrupts the network, Difficult to troubleshoot

4. Mesh Topology

Every device is connected to every other device.

Advantages:

• Very reliable, multiple paths for data, If one connection fails, data takes another path, Good security (dedicated connections)

Disadvantages:

• Very expensive (lots of cables and ports), Complex to set up and maintain, Practical only for small networks

5. Tree (Hierarchical) Topology

A combination of star and bus topologies. It has a root node and branches like a tree.

Advantages:

• Easy to expand, Point-to-point connections, Easy to manage

Disadvantages:

• If the root node fails, the entire network is affected, More cabling required, Difficult to configure

Topology Comparison

Feature	Bus	Star	Ring	Mesh	Tree
Cable used	Least	Moderate	Moderate	Most	Moderate
Central device	No	Yes	No	No	Yes
Failure impact	Entire network	One device	Entire network	One connection	Branch
Cost	Low	Moderate	Moderate	Very high	Moderate
Ease of troubleshooting	Difficult	Easy	Difficult	Easy	Moderate
Most common	No	Yes	No	No	No

Network Devices

Device	Purpose
Hub	Connects devices in a LAN, sends data to all ports (not intelligent)
Switch	Connects devices in a LAN, sends data only to the intended port (intelligent)
Router	Connects different networks, routes data between them using IP addresses
Modem	Converts digital signals to analog and vice versa for Internet connectivity
Gateway	Connects networks with different protocols
Bridge	Connects two network segments, filters traffic
Repeater	Amplifies weak signals to extend network range
Access Point	Provides wireless connectivity (Wi-Fi)
NIC	Network Interface Card, hardware that connects a computer to a network

Hub vs Switch vs Router

Feature	Hub	Switch	Router
Layer	Physical layer	Data link layer	Network layer
Intelligence	Not intelligent	Intelligent	Most intelligent
Data sending	Sends to all ports	Sends to specific port	Routes between networks
Collision	Collisions occur	No collisions	No collisions
Cost	Cheapest	Moderate	Most expensive
Use	Almost obsolete	Within a LAN	Between networks

Transmission Media

Guided (Wired) Media

Type	Description	Speed	Distance
Twisted Pair	Two insulated copper wires twisted together	Up to 10 Gbps	Short (100 m)
Coaxial Cable	Central conductor surrounded by insulation and shield	Up to 1 Gbps	Medium (500 m)
Fiber Optic	Glass/plastic fibers carrying light signals	Up to 100 Gbps	Very long (100+ km)

Unguided (Wireless) Media

Type	Description	Range
Radio Waves	Used for Wi-Fi, Bluetooth, mobile networks	Varies widely
Microwaves	Point-to-point communication, satellite	Long range
Infrared	Short-range communication (remote controls)	Very short
Satellite	Communication via orbiting satellites	Global

Twisted Pair vs Coaxial vs Fiber Optic

Feature	Twisted Pair	Coaxial	Fiber Optic
Material	Copper wires	Copper with shield	Glass/plastic fibers
Speed	Moderate	Moderate	Very high
Distance	Short (100 m)	Medium (500 m)	Long (100+ km)
Cost	Cheapest	Moderate	Most expensive
Interference	Susceptible	Less susceptible	Immune
Weight	Light	Medium	Lightest
Usage	Office networks	Cable TV	Internet backbone

Client-Server vs Peer-to-Peer

Feature	Client-Server	Peer-to-Peer
Central server	Yes	No
Dedicated roles	Server serves, clients request	All computers are equal
Security	Centralized, stronger	Decentralized, weaker
Cost	Higher (server required)	Lower
Scalability	Highly scalable	Limited
Management	Centralized	Each computer manages itself
Example	School network, company website	File sharing (BitTorrent)

Important Questions

Q1. Differentiate between LAN, MAN, and WAN.

LAN covers a small area (building/campus, up to 1-2 km) with high speed and low cost, owned by one organization (e.g., school lab). MAN covers a city (up to 100 km) with moderate speed and cost (e.g., city cable network). WAN covers countries or worldwide with variable speed and high cost, operated by ISPs (e.g., the Internet).

Q2. What is the difference between a hub and a switch?

A hub sends incoming data to all connected ports regardless of the destination, causing unnecessary traffic and collisions. A switch is intelligent, it reads the destination address and sends data only to the intended port, reducing traffic and improving performance. Switches have largely replaced hubs in modern networks.

Q3. Compare star and bus topologies.

In star topology, all devices connect to a central switch/hub. If one cable fails, only one device is affected, but if the central device fails, the entire network fails. In bus topology, all devices connect to a single backbone cable. It uses less cable and is cheaper, but if the backbone fails, the entire network fails. Star topology is more common in modern networks.

Q4. What is fiber optic cable? Why is it preferred over copper?

Fiber optic cable uses thin glass or plastic fibers to transmit data as pulses of light. It is preferred over copper because it offers much higher speeds (up to 100 Gbps), longer transmission distances (100+ km), immunity to electromagnetic interference, better security (difficult to tap), and lighter weight. However, it is more expensive than copper cables.

Quick Revision

• Network sizes: PAN < LAN < MAN < WAN
• LAN = building/campus; MAN = city; WAN = worldwide, Most common topology: Star (all connect to central switch)
• Hub sends to all; Switch sends to specific port; Router routes between networks
• Modem converts digital to analog and vice versa, Wired media: Twisted pair, Coaxial, Fiber optic (fastest), Wireless media: Radio waves, Microwaves, Infrared, Satellite
• Client-Server has a central server; Peer-to-Peer has equal computers