JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD MCA 2017 COMPUTER NETWORKS Previous Question Paper (August - 2017 - R09)

An Analog Signal is a continuous waveform that changes smoothly over time, representing information through variations in amplitude, frequency, or phase. It can take on an infinite number of values within a given range. A common example is the human voice or a sine wave transmitted over traditional telephone lines.

A Digital Signal is a discrete signal that represents information as a sequence of separate values, typically binary digits (0s and 1s). It changes in steps rather than continuously, providing better noise immunity and easier error detection. A common example is the data transmitted within a computer or across a digital network, such as pulses representing voltage levels in a circuit.

The ISO/OSI model defines seven layers, each with specific responsibilities:

• Physical Layer: Handles the transmission of raw bit streams over a physical medium, defining electrical, mechanical, and functional specifications.
• Data Link Layer: Provides node-to-node data transfer, framing, physical addressing, and error control to ensure reliable transmission between adjacent devices.
• Network Layer: Manages logical addressing, routing packets across multiple networks, and congestion control.
• Transport Layer: Ensures end-to-end communication, segmentation of data, flow control, and error correction for reliable data delivery.
• Session Layer: Establishes, manages, and terminates connections (sessions) between applications on different hosts.
• Presentation Layer: Handles data translation, encryption, compression, and formatting to ensure compatibility between different data representations.
• Application Layer: Provides network services directly to end-user applications, such as file transfer (FTP), email (SMTP), or web browsing (HTTP).