Question

Layer-3 in OSI is composed of the following: (A) Physical Topology (B) Framing (C) Physical Addressing (D) Synchronization of bits Choose the correct answer from the options given below:

• A. (A) and (D) only
• B. (B) and (C) only
• C. (A), (B), (C) and (D)
• D. None of the above. The correct answer is Logical Addressing and Routing.

Hint:

Associate layers with their address types: Layer 2 (Data Link) uses physical (MAC) addresses. Layer 3 (Network) uses logical (IP) addresses. This is a key distinction.

Answer 1

The Correct Option is D

Step 1: Identify Layer 3 of the OSI model. Layer 3 is the Network Layer. Its primary responsibilities are logical addressing (e.g., IP addresses) and routing packets across networks.

Step 2: Analyze the given options and identify which layer they belong to. \[\begin{array}{rl} \bullet & \text{(A) Physical Topology: The arrangement of nodes and cables. This is a concept of the Physical Layer (Layer 1).} \\ \bullet & \text{(B) Framing: The process of dividing data into frames. This is a key function of the Data Link Layer (Layer 2).} \\ \bullet & \text{(C) Physical Addressing: Using MAC addresses. This is a function of the Data Link Layer (Layer 2).} \\ \bullet & \text{(D) Synchronization of bits: Ensuring the sender and receiver are synchronized on the bit level. This is a function of the Physical Layer (Layer 1).} \\ \end{array}\]

Step 3: Conclude. None of the provided options (A, B, C, D) are functions of the Network Layer (Layer 3). Therefore, none of the combinations are correct.