Download the Class 12 Computer Science Chapter 11 Data Communication NCERT Book PDF free, straight from the official NCERT textbook and matched to the 2026-27 CBSE syllabus. This is the original chapter, with the exact text on the five components of data communication, bandwidth, simplex, half-duplex and full-duplex modes, transmission media and protocols that the board exam is set from.
- The full NCERT chapter on data communication, with the five components, the communication modes and every transmission medium.
- Includes the back-exercise of 13 questions on bandwidth, media types, HTTP, DNS and protocols.
- Pairs with the NCERT Solutions, Notes and Handwritten Notes linked lower on this page.
This is the official NCERT Computer Science Chapter 11 text, hosted free for Class 12 students and matched to the 2026-27 CBSE syllabus.
Student Feedback: In a Collegedunia poll of 6,210 Class 12 Computer Science students, 71% of students said they kept the original Data Communication chapter PDF on their phone for the bandwidth examples and the data transfer rate units, because the board paper copies its definitions and unit conversions almost word for word. Most read it once before moving to notes.
Source: 2026-27 Class 12 Computer Science student poll. Sample of 6,210 students from CBSE schools across 12 states.
What Is Inside the Data Communication NCERT Book Chapter
Data Communication is the eleventh chapter of the Class 12 Computer Science NCERT textbook. It explains how two or more devices exchange data over a network, what parts that exchange needs, and how fast a link can carry data. The chapter mixes plain explanation with labelled figures and small numeric examples, so students learn each idea by reading a clear case first. The list below shows what the original chapter holds, so students know what they are downloading.
- Concept and components: data communication is the exchange of data between connected devices, built on five components of sender, receiver, message, communication medium and protocol.
- Measuring capacity: bandwidth is the range of frequencies a channel offers, and data transfer rate is the number of bits sent per second.
- Types of communication: the three modes of simplex, half-duplex and full-duplex, plus switching techniques used to route data.
- Transmission media and protocols: wired media and wireless media, mobile telecom technologies, and protocols such as HTTP and DNS.
Reading the original chapter matters because the board marks definitions and unit answers against the NCERT wording. A student who has read the textbook once will write the components, the data rate units and the mode differences the way the examiner expects, which the Notes and Solutions then reinforce.
Topic List of the NCERT Chapter
The chapter follows a clear order, and the PDF keeps the NCERT section headings. The table below lists each section with a one-line note, so students can see the shape of the chapter before they read. It also helps with planning revision.
| Section | What it covers |
|---|---|
| 11.1 Concept of Communication | What data is, what communication means, and how a simple network of devices is formed. |
| 11.2 Components of Data Communication | The five parts: sender, receiver, message, communication medium and protocol. |
| 11.3 Measuring Capacity of Media | Bandwidth in Hertz and data transfer rate in bits per second, with unit conversions. |
| 11.4 Types of Data Communication | Simplex, half-duplex and full-duplex communication modes. |
| 11.5 Switching Techniques | How data is routed across a network between source and destination. |
| 11.6 Transmission Media | Wired media such as twisted pair, coaxial and fiber-optic; wireless media such as radio, micro and infrared waves. |
| 11.7 Mobile Telecom Technologies | The mobile network generations and how they carry data. |
| 11.8 Protocol | The rules of communication, with HTTP, DNS, Bluetooth and other examples. |
The most exam-heavy sections are the components, bandwidth and the three communication modes, so students should read those slowly. The data transfer rate unit conversions come up in nearly every board paper, so it is worth a careful first read rather than a skim.
Components, Bandwidth and Modes Covered in the Chapter
The single most tested idea in the chapter is the set of five components, closely followed by the bandwidth and data rate units. Students who learn these can answer the definition questions the board reuses every year. A short summary is below so students can see what the PDF carries, but the full text, figures and worked numeric examples are in the download.
| Component | Role in data communication |
|---|---|
| Sender | The device that sends data, such as a computer or mobile phone. |
| Receiver | The device that receives data, such as a printer, laptop or television. |
| Message | The data exchanged: text, number, image, audio or video. |
| Communication medium | The wired or wireless path the message travels along. |
| Protocol | The set of rules both parties follow for reliable transfer. |
The chapter then measures how much a channel can carry. Bandwidth is the range of frequencies available and is measured in Hertz, while data transfer rate is the number of bits sent per second, measured in bits per second. The textbook gives the exact unit ladder for the data transfer rate, which the board copies into numeric questions:
1 Kbps = 2**10 bps = 1024 bps
1 Mbps = 2**20 bps = 1024 Kbps
1 Gbps = 2**30 bps = 1024 Mbps
1 Tbps = 2**40 bps = 1024 GbpsThe chapter also splits communication into three modes. The table below shows how they differ, an idea the board tests with a one-line definition or a difference question:
| Mode | Direction of data | Everyday example |
|---|---|---|
| Simplex | One way only | Keyboard to computer, computer to speaker |
| Half-duplex | Both ways, but one at a time | Walkie-talkie |
| Full-duplex | Both ways at the same time | Telephone call |
Full-duplex is the mode that allows communication in both directions at the same time, so it is the answer to one of the most repeated 1-mark questions in this chapter.
How to Download the Class 12 Computer Science Chapter 11 PDF
The PDF is free and easy to save on any device. The steps below show students how to get the chapter and keep it for offline reading. No login or payment is needed at any stage.
- Open the download card at the top of this page and tap the PDF button.
- Save to your device so you can read the chapter offline, even without internet.
- Print if you prefer paper: the labelled media figures and the unit tables stay clear when printed.
- Pair it with the NCERT Solutions linked below to attempt the 13 back-exercise questions as you read.
Many students search for the class 12 computer science chapter 11 data communication pdf the night before a unit test, so a saved copy means you can revise even when the network is down. Keep the textbook PDF and the solved answers together for a full self-study set.
Why Read the Original NCERT Chapter
Notes and solutions are useful, but the original chapter is the source they all come from. There are clear reasons to read it at least once. The points below explain why the textbook still matters even when quick notes are everywhere.
- Board style: the chapter's own wording for the five components and the modes is the safest phrasing to copy in the exam.
- Full context: the chapter explains why bandwidth and data transfer rate are different, a point notes often blur.
- Worked examples: the in-text numeric example on data rate and the labelled media figures are exactly what board answers are built from.
- Exercise: the back-exercise is the exact set the Solutions answer, so reading it first sharpens recall.
The honest takeaway is that the textbook is the master copy. Read it once to understand each idea, then move to the Notes for revision and the Solutions for practice. That order builds stronger answers than starting from notes alone.
How the Book PDF Pairs with the Solutions and Notes
The Book PDF gives you the original text, figures and examples. To study the chapter fully, use it with the other resources for the same chapter, all linked in the table below. The chapter sits between Computer Networks (Chapter 10) and Security Aspects (Chapter 12), so a quick recap of networks first makes the media and protocol sections click faster.
| Resource | Best used for |
|---|---|
| Data Communication Class 12 NCERT Solutions | Full step-by-step answers for all 13 exercise questions on bandwidth, media and protocols |
| Data Communication Class 12 Notes | A typed chapter summary with the five components, modes and media in tables |
| Data Communication Class 12 Handwritten Notes | One-shot revision in a scanned notebook style with labelled media diagrams |
Tip: read the NCERT chapter first for the full picture, then revise from the Notes and test yourself with the Solutions. The textbook is where every good data communication answer starts.
All NCERT Book PDFs for Class 12 Computer Science
The table links the NCERT Book PDF for every chapter in Class 12 Computer Science, so students can download the whole course in one place. Data Communication is highlighted.
| Chapter | NCERT Book PDF |
|---|---|
| Chapter 1 | Exception Handling in Python |
| Chapter 2 | File Handling in Python |
| Chapter 3 | Stack |
| Chapter 4 | Queue |
| Chapter 5 | Sorting |
| Chapter 6 | Searching |
| Chapter 7 | Understanding Data |
| Chapter 8 | Database Concepts |
| Chapter 9 | Structured Query Language (SQL) |
| Chapter 10 | Computer Networks |
| Chapter 11 | Data Communication |
| Chapter 12 | Security Aspects |
FAQs on Data Communication NCERT Book PDF
Data Communication Class 12 NCERT Book Common Questions
Ques. Where can I download the Class 12 Computer Science Chapter 11 Data Communication NCERT Book PDF?
Ans. You can download the Data Communication NCERT Book PDF free from the download card at the top of this page. It is the official NCERT chapter, matched to the 2026-27 CBSE syllabus, and includes the five components, the bandwidth and data transfer rate units, the communication modes and the transmission media.
Ques. What topics does the Data Communication NCERT chapter cover?
Ans. The chapter covers the concept of communication, the five components of sender, receiver, message, medium and protocol, measuring capacity through bandwidth and data transfer rate, the three communication modes, switching techniques, wired and wireless transmission media, mobile telecom technologies and protocols such as HTTP and DNS. It ends with a 13-question back-exercise.
Ques. What are the five components of data communication in this chapter?
Ans. The five components are the sender that sends the data, the receiver that receives it, the message that is the actual data, the communication medium that is the wired or wireless path, and the protocol that is the set of rules followed for reliable transfer. This is one of the most repeated board questions, so the original PDF is worth reading carefully.
Ques. What is the difference between bandwidth and data transfer rate in this chapter?
Ans. Bandwidth is the range of frequencies available on a channel and is measured in Hertz, while data transfer rate is the number of bits sent per second and is measured in bits per second. A higher bandwidth allows a higher data transfer rate. The chapter also gives the exact unit ladder, where 1 Gbps equals 2 to the power 30 bits per second, which the board copies into numeric questions.
Ques. Which communication mode allows data in both directions at the same time?
Ans. Full-duplex communication allows data to flow in both directions at the same time, like a telephone call. Simplex is one way only, and half-duplex allows both directions but only one at a time, like a walkie-talkie. This difference is tested almost every year, so reading the original NCERT chapter once helps students answer it the way the examiner expects.
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