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Data Communication Class 12 Computer Science Chapter 11 CBSE Notes 2025-26

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Get CBSE Class 12 Computer Science Notes PDF For Quick Revision

CBSE Class 12 Computer Science Notes Chapter 11 are designed to make revision quick and effective for all students. With the help of these concise cbse 12 computer science notes, you can easily refresh the important topics before exams.


This chapter covers key computer science concepts relevant to your syllabus, making it simple to understand and remember. The cbse class 12 computer science notes pdf will provide stepwise explanations and important pointers for all key points.


Use the Vedantu cbse class 12 computer science chapter wise notes pdf to organise your revision and be better prepared. These notes are tailored for easy last-minute review and strong exam preparation.


CBSE Class 12 Computer Science Notes PDF For Better Revision

Data communication is the process of exchanging data between networked devices such as computers, smartphones, servers, and printers. This data can be in the form of text, images, audio, video, or other media. For communication to occur, devices must be capable of both sending and receiving data over various kinds of communication media.


A network is formed when multiple devices are interconnected, often through cables or wireless signals. These devices use specific paths, called transmission media, to share information quickly and accurately. The reliable transmission of messages across networks forms the backbone of modern computing and daily communication.

Concept of Data Communication

Data communication consists of two key ideas: 'data', meaning any information to be sent, and 'communication', meaning the act of sending or receiving that data. Whether messaging on a phone or printing from a computer, these steps are always involved.

  • Data is any text, number, image, audio, or video.
  • Communication is sending or receiving this data over a network.
  • Devices involved include computers, printers, mobile phones, servers, and network switches.

In practice, a simple network may link a computer, printer, server, and switch, using wires or wireless connections. The connection media determines how fast and reliably data moves from one device to another.

Components of Data Communication

Effective data communication relies on five main components that enable smooth exchange between devices. Each plays a unique role in the transfer process.

  • Sender: Device that originates and sends data (computer, smartphone, camera).
  • Receiver: Device that receives data from the network (printer, TV, computer, mobile).
  • Transmission Media: The connecting path—wired like ethernet cables, or wireless like satellite links or wifi.
  • Message: The actual data to be sent; can include text, images, audio, or video.
  • Protocols: Agreed rules or procedures that ensure consistent, reliable delivery of data (like HTTP or Ethernet).

Both sender and receiver are called nodes. Communication works properly only if both follow the same protocol and use compatible transmission media.

Measuring Communication Capacity

The ability of a transmission medium to carry data is measured using two main terms: bandwidth and data transfer rate. These directly affect the speed and quality of data transfer across the network.

  • Bandwidth: The range of available frequencies in a channel, measured in Hertz (Hz). Higher bandwidth means faster possible data transfer.
  • Data Transfer Rate: The amount of data (in bits) transmitted per second, often expressed in bits per second (bps), Kbps, Mbps, Gbps, etc.

For example, 1 Kbps means 1024 bits per second; 1 Mbps equals 1024 Kbps, and so on. High data transfer rates are essential for applications like streaming or video calls.

Types of Data Communication

Depending on the direction and timing of data flow, communication can be unidirectional or bidirectional, and can happen either one-way at a time or in both directions at once.

  • Simplex: Data moves only in one direction, like from keyboard to computer. The receiver cannot send back data to the sender.
  • Half-duplex: Devices take turns to send and receive data, such as in walkie-talkies.
  • Full-duplex: Devices can send and receive data at the same time. Examples include telephones and mobile calls.

Understanding these modes helps in choosing the right technology for a given communication need, from broadcasting TV signals to enabling group video calls.

Switching Techniques

Switching determines how data is routed through a network of many devices. It ensures efficiency and reduces the need for direct connections between every pair of devices.

  • Circuit Switching: Reserves a dedicated path for the entire communication, like early telephone networks. Once established, it remains till the conversation ends.
  • Packet Switching: Data is divided into packets which may travel independently across the network and are combined at the destination. This method is more flexible and makes better use of available resources.

Technologies like VoIP and VoLTE employ advanced switching techniques to carry voice and multimedia through the Internet or cellular networks efficiently.

Transmission Media: Wired and Wireless

The medium carrying the data may be physical cables (wired) or use electromagnetic waves (wireless). Choosing between wired and wireless depends on cost, speed, convenience, and required range.

  • Wired Media: Includes twisted pair cable (simple, used in telephones), coaxial cable (better shielding and bandwidth, used for TV and internet), and optical fiber (very fast, uses light, immune to electrical interference, but costly and delicate).
  • Wireless Media: Uses radio waves, microwaves, and infrared spectrum for data transmission. Popular for mobility and convenience in places without cable infrastructure.

Each type of medium is better suited for certain ranges, speeds, and environments. For example, optical fiber is used for backbone connections, while Wi-Fi serves homes and offices.

Wireless Communication Technologies

Wireless technologies let devices communicate without direct cables by using electromagnetic waves of different frequencies. Common standards include Bluetooth and Wi-Fi.

  • Bluetooth: Short range (up to 10 meters), links smartphones, wireless headsets, and laptops, suitable for personal area networks (PANs).
  • Wi-Fi: Enables devices to connect to local area networks wirelessly, allowing flexible internet access in homes, schools, and public spaces using Access Points.
  • WiMax: Used for larger area coverage, such as cities or towns (MANs), with higher data rates than Wi-Fi.

Wireless transmission can use radio waves (for broadcasting), microwaves (for line-of-sight communication), or infrared (for devices in the same room, like remotes).

Mobile Telecommunication Technologies

Mobile communication has advanced through generations, improving quality, speed, and features. Each generation brought new capabilities.

  • 1G: Analog voice calls only.
  • 2G: Digital voice, SMS, MMS, better security.
  • 3G: Higher data rates, supports calls and internet browsing.
  • 4G: Even faster, supports HD video streaming and mobile broadband.
  • 5G: Extremely high speed (Gbps), supports Internet of Things (IoT) and smart devices.

This progression has made features like high-speed internet, video calling, and smart connected devices common in daily life.

Protocols in Data Communication

Protocols are essential for organized and reliable exchange of data between devices. They define how data is formatted, transmitted, and received, and how errors are handled.

  • Flow Control: Manages data rate differences between sender and receiver.
  • Access Control: Decides which device can send data at any time to prevent collisions.
  • Addressing: Ensures messages reach the correct recipient and in the correct order.

Some widely used protocols include:

  • HTTP: Foundation for web browsing, follows request-response structure.
  • FTP: Allows secure file transfer between computers.
  • PPP: Creates a direct link between two nodes, such as computer to modem.
  • SMTP: Handles delivery and management of email messages.
  • TCP/IP: Governs data transmission across the Internet, breaking down messages, and routing them accurately.

Devices on the internet use unique IP addresses and follow TCP/IP rules, ensuring messages arrive correctly, even if the path changes along the network.

Key Takeaways
  • Data communication links devices to share information efficiently.
  • Main elements include sender, receiver, message, channel, and protocol.
  • Wired and wireless media have unique uses, advantages, and limitations.
  • Understanding types of communication and bandwidth is vital for exam readiness.
  • Switching and protocols make communication organized and reliable.
  • Progress in mobile technologies has transformed digital life and connectivity through each generation.

Reviewing these points ensures a clear understanding of core concepts in data communication, which are important for CBSE Class 12 Computer Science assessments.

Class 12 History Chapter 11 Notes – Data Communication: Quick Revision Guide

Prepare for exams easily with these Class 12 Data Communication notes, covering all important concepts and protocols outlined in Chapter 11. Clear definitions and comparative tables help students understand data transmission modes, switching techniques, and essential protocols. Reviewing these points aids in building a strong foundation for the Computer Science syllabus.


From communication components to wired and wireless media, these chapter notes are structured for fast recall and revision. Students can use them to quickly practice exam-style questions on bandwidth, transmission, and real-world applications of protocols like HTTP and TCP/IP.


FAQs on Data Communication Class 12 Computer Science Chapter 11 CBSE Notes 2025-26

1. What is covered in Cbse Class 12 Computer Science Notes Chapter 11?

CSE Class 12 Computer Science Notes Chapter 11 includes step-by-step solutions, key definitions, diagrams, and explanations to support efficient revision and exam preparation.

2. How can I revise Class 12 Computer Science Chapter 11 quickly?

Use concise revision strategies and focus on:

  • Summarising key definitions and concepts
  • Practising stepwise solutions for all exercises
  • Reviewing diagrams and their labels
  • Following a 1-day or 3-day quick revision plan

3. Are stepwise answers important for CBSE board exams?

Yes. Stepwise answers match the CBSE marking scheme and help you earn full marks for each answer component in Class 12 Computer Science Chapter 11.

4. How do I structure long answers for better marks in board exams?

Divide your answer into clear steps:

  1. Start with an introduction
  2. Present each point in a separate paragraph
  3. Include definitions and diagrams where needed
  4. Summarise with a concluding statement

5. What are the most important topics from Class 12 Computer Science Chapter 11?

The most important topics include:

  • Key definitions and principles
  • Typical diagrams or flowcharts
  • Stepwise exercise problems
  • CBSE marking criteria

6. Do diagrams and definitions have to be included in every answer?

No. Diagrams and definitions are only necessary for questions that explicitly ask for them or when they clarify your answer, as per CBSE guidance.

7. Where can I download the Class 12 Computer Science Chapter 11 solutions PDF?

The solutions PDF for Chapter 11 is available for free download on the main notes page for offline revision.

8. Are these notes sufficient for scoring full marks in the CBSE board exam?

These notes are designed to align with CBSE requirements, covering all key points, marking scheme steps, and exam-focused questions for maximum scores.

9. How should I label diagrams or flowcharts in Chapter 11 Computer Science answers?

Label diagrams neatly using:

  • Standard conventions and terminology
  • Clear arrows or markers
  • Legible handwriting

This helps avoid losing simple marks.

10. Do examiners give partial marks for correct steps even if the final answer is wrong?

Yes. CBSE examiners award partial marks for each correct step according to the marking scheme, even if your final answer is not fully correct.

11. Which questions from Class 12 Computer Science Chapter 11 are likely to appear in school exams?

Questions often asked include:

  • Key definitions
  • Stepwise numerical problems
  • Diagram-based explanations
  • Case-based or assertion-reason questions

12. How does reviewing exercise-wise solutions help during revision?

Exercise-wise solutions show how to answer according to textbook structure, making it easier to practice and check your answers against model solutions.