(SEM. VII) THEORY EXAMINATION 2017-18 DATA COMMUNICATION NETWORKS

SECTION A

(Short answers – explained clearly)

1. What is the difference between Guided and Unguided Media?

Guided media refers to communication channels where data signals travel through a physical path such as twisted pair cables, coaxial cables, or optical fiber. These media provide controlled transmission, higher security, and less interference. Unguided media, on the other hand, transmits data through free space using electromagnetic waves. Examples include radio waves, microwaves, and satellite communication. Unguided media is easier to deploy but is more prone to noise and security issues.

2. Why do we use layered protocol? Give reasons.

Layered protocols are used to divide the complex task of network communication into smaller, manageable layers. Each layer performs a specific function and interacts only with adjacent layers. This approach simplifies design, allows independent development of layers, and makes troubleshooting easier. It also ensures interoperability, as changes in one layer do not affect others.

SECTION B

(Medium answers – conceptual explanation)

3. What do you mean by layered architecture? Explain the role of each layer in the OSI model.

Layered architecture is a design approach in which network communication is divided into multiple layers, each responsible for a specific function. In the OSI model, the physical layer handles transmission of raw bits, the data link layer ensures error-free data transfer, and the network layer manages routing. The transport layer provides reliable end-to-end delivery, while the session layer manages sessions. The presentation layer handles data formatting and encryption, and the application layer provides network services to users. This structure ensures organized and efficient communication.

4. Explain routing algorithms in detail.

Routing algorithms determine the best path for data packets to travel from source to destination. These algorithms consider factors such as distance, cost, and network congestion. Common routing approaches include distance vector routing, where routers share routing tables with neighbors, and link state routing, where routers have complete network topology information. Efficient routing algorithms improve network performance and reliability.

SECTION C

(Long answers – detailed explanation)

5. What is line coding technique? Explain and compare different line coding techniques.

Line coding is the process of converting digital data into digital signals suitable for transmission over a communication channel. Different techniques such as NRZ, Manchester, and Bipolar encoding are used. NRZ is simple but suffers from synchronization problems. Manchester encoding provides better synchronization by combining clock and data but requires higher bandwidth. Bipolar encoding reduces DC components and improves error detection. The choice of line coding depends on bandwidth efficiency and synchronization needs.

6. Explain IPv4 and IPv6 addressing.

IPv4 addressing uses 32-bit addresses divided into network and host parts, allowing about 4.3 billion unique addresses. Due to rapid growth of the internet, IPv4 addresses became insufficient. IPv6 was introduced with 128-bit addresses, providing a vastly larger address space. IPv6 also improves security, supports auto-configuration, and simplifies routing. IPv6 is considered the future of internet addressing.