Computer Networks 2 of Class 12 CBSE code 083

Computer Networks

CBSE Class 12 Computer Science (083)

80/20 Rule in Networking

Definition

The 80/20 Rule states that nearly 80% of network traffic remains inside the Local Area Network (LAN) while only 20% travels outside through routers to other networks or the Internet.

Explanation

• 80% Local Traffic – File sharing, printer access, local servers.
• 20% External Traffic – Internet browsing, cloud services and communication with remote networks.

Advantages

• Improves network performance.
• Reduces congestion.
• Efficient bandwidth utilization.
• Less network delay.
• Reliable communication.

Computer
⬇
NIC
⬇
Switch
⬇
Bridge (If Needed)
⬇
Router
⬇
Modem
⬇
ISP
⬇
Gateway (If Needed)
⬇
Internet

Communication Media and Devices

Scenario	Media	Device	Reason
Home Network	Wi-Fi / UTP	Modem, Router	Internet Connection
School Lab	UTP Cable	Switch	Fast LAN
Office	Optical Fiber	Switch, Router	Department Communication
Bank	Optical Fiber	Router, Gateway	Secure Network
Hospital	Fiber / UTP	Router, Switch	Medical Records
University	Fiber + Wi-Fi	Router, Access Point	Campus Network
Mobile Network	Microwave	Cell Tower	Wireless Communication
Satellite	Microwave	Satellite, Modem	Remote Communication
TV Broadcast	Radio Wave	Broadcast Tower	Signal Transmission
Video Conference	Fiber / Wi-Fi	Router	High Speed Data

Communication Media Selection

Requirement	Media
Short Distance	UTP Cable
Long Distance	Optical Fiber
Wireless	Wi-Fi
Mobile Communication	Microwave
Satellite Communication	Microwave
TV Broadcasting	Radio Waves

Networking Device Selection

Requirement	Device
Connect LAN	Switch
Connect Networks	Router
Internet	Modem
Extend Signal	Repeater
Connect LAN Segments	Bridge
Different Protocols	Gateway
Connect Computer	NIC
Wireless Access	Access Point
Broadcast Data	Hub

CBSE Scenario-Based Questions

1. School Computer Lab

Media: UTP Cable
Device: Switch

2. Bank Branch

Media: Optical Fiber
Device: Router + Gateway

3. Home Wi-Fi

Media: Wi-Fi
Device: Modem + Wireless Router

4. TV Broadcasting

Media: Radio Waves
Device: Broadcasting Tower

5. Remote Village Internet

Media: Microwave
Device: Satellite Dish + Modem

Exam Tip

1. Identify the distance.
2. Select suitable communication media.
3. Choose the correct networking device.
4. Write one reason.