Ch 11Data Communication — Class 12 Computer Science, concept-first.

The word "Data Communication" is built from two simpler ideas: Data and Communication. Data refers to any information that can be stored or transmitted — this includes text, images, audio, video, and…

The five essential components of any data communication system are the sender, receiver, message, communication medium, and protocol.

The capacity of a communication channel is simply the maximum amount of signals or traffic it can carry. In data communication, the transmission medium is also called a channel.

The capacity of a communication channel to carry data is not unlimited. Every channel — whether it is a copper wire, an optical fibre, or the air for wireless signals — can only handle a certain range…

Data moves across a communication channel in the form of signals. Each signal can carry one or more bits.

Data communication takes place in the form of signals exchanged between two or more computing devices or nodes.

Simplex communication is the simplest form of data flow between two devices. It is strictly one-way or unidirectional — one device is always the sender, and the other is always the receiver.

Half-duplex communication is a two-way or bidirectional mode of data transmission between two devices. Both devices can send and receive data or control signals, but not at the same time.

Full-duplex communication is two-way, bidirectional data transfer where both devices can send and receive data at the same time.

In a network with multiple devices, the challenge is connecting a specific sender and receiver so that one-to-one communication is possible.

Circuit switching is the oldest method of data communication, borrowed directly from the traditional telephone system.

In packet switching, the message to be sent is not transmitted as one continuous stream. Instead, it is broken down into smaller, manageable units called packets.

A transmission medium is anything that can carry signals or data between a source (transmitter) and a destination (receiver).

Wired transmission media are any physical links that carry data in the form of signals. The three most common types are twisted pair cable, coaxial cable, and fibre optic cable.

Wireless transmission media use electromagnetic signals that travel through the air, not through any physical cable.

Wireless technologies let devices communicate without physical cables. The book discusses two main types: Bluetooth and Wireless LAN (Wi-Fi).

The mobile phone network is the most widely used network in the world today. Its real power is the ability to stay connected while moving — making voice calls, sending instant messages, or accessing t…

Imagine two people trying to have a conversation — one speaks only Hindi, the other only Japanese, and they're shouting across a noisy room.

A protocol is a set of rules that governs how data is sent, received, and interpreted across a network.

HTTP stands for HyperText Transfer Protocol. It is the primary protocol used to access the World Wide Web.

File Transfer Protocol (FTP) is the standard network protocol used to transfer files from one computer to another over a TCP-based network like the Internet.

The Point to Point Protocol (PPP) is a communication protocol that creates a dedicated, direct connection between two devices.

SMTP is the protocol that makes email work. It is not concerned with what you write in an email — only with getting that email to the right place, much like the postal service handles an envelope with…

TCP/IP stands for Transmission Control Protocol / Internet Protocol. It is not a single protocol but a set of standardised rules that governs how data travels across the Internet.

- Data communication is the exchange of data between two or more networked or connected devices, such as laptops, PCs, printers, and routers.

Questions from official CBSE sample papers.