Computer Network Notes – Class 11 & 12
This post contains complete Computer Network chapter notes for CBSE Class 11 and 12 Computer Science and Informatics Practices. All topics are explained in a simple, student-friendly format.
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1. Introduction
A computer network is a group of connected computers that can share data, resources, and communication. It can be wired or wireless.
2. Computer Network Overview
Computer networks are used to share files, internet, printers, and more.
2.1 Advantages of Computer Network
- File and printer sharing
- Centralized data storage
- Easy communication and data access
2.2 Disadvantages of Computer Network
- Security threats
- Virus spreading risks
- Requires proper maintenance
3. Evolution of Network
From ARPANET to today's high-speed internet, networks have evolved for better communication, data sharing, and access across the globe.
4. How Does the Internet Work?
The internet connects multiple networks worldwide using protocols like TCP/IP and devices such as routers, modems, and servers.
4.1 Basic Network Terminology
- Node - any connected device
- Router - directs data between networks
- Server - provides data or services
5. Components of Data Communication
- Message
- Sender
- Receiver
- Medium
- Protocol
6. Sending Data Across a Network
6.1 Network Switching
Switching is the method of transferring data from one device to another in a network.
6.2 Circuit Switching vs Packet Switching
| Feature | Circuit Switching | Packet Switching |
|---|---|---|
| Path | Dedicated path | Dynamic path |
| Usage | Telephone network | Internet communication |
| Speed | Stable once connected | Efficient for data transfer |
6.7 Data Communication Terminologies
- Bandwidth
- Latency
- IP Address
- MAC Address
6.8 Network Devices
- Router
- Switch
- Hub
- Modem
- Access Point
6.9 Types of Networks
- Personal Area Network (PAN)
- Local Area Network (LAN)
- Metropolitan Area Network (MAN)
- Wide Area Network (WAN)
6.10 Network Topologies
- Star Topology
- Bus Topology
- Ring Topology
- Mesh Topology
- Tree Topology
6.11 Communication Media
6.11.1 Guided (Wired)
- Twisted Pair
- Coaxial Cable
- Fiber Optic Cable
6.11.2 Unguided (Wireless)
- Radio Waves
- Microwaves
- Infrared
- Wi-Fi
6.12 Network Protocols
- HTTP / HTTPS
- FTP
- SMTP / POP3
- TCP / IP
6.13 Web Services
- 6.13.1 World Wide Web (WWW)
- 6.13.2 HyperText Markup Language (HTML)
- 6.13.3 Extensible Markup Language (XML)
- 6.13.4 Domain Name
- 6.13.5 URL
- 6.13.6 IP Address
- 6.13.7 Website
- 6.13.8 Web Page
- 6.13.9 Web Browser
- 6.13.10 Web Server
- 6.13.11 Web Hosting
6.14 Setting Up a Computer Network - Example
- Plan the network and number of devices
- Choose network devices (modem, router, switch)
- Lay cables or set up wireless access
- Assign IP addresses
- Secure the network and test connectivity
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