How do routers and switches differ in function and OSI layer?

• A. Switches operate at the Application layer to manage sessions; routers operate at the Transport layer to ensure delivery.
• B. Switches operate at the Data Link layer to forward frames by MAC; routers operate at the Network layer to route packets by IP between networks.
• C. Switches route packets across networks; routers forward frames within a LAN.
• D. Switches operate at the Physical layer to transmit bits; routers operate at the Data Link layer to handle frames.

Answer: (B)

The main idea is that devices operate at different layers of the OSI model to perform distinct tasks. A switch works at the Data Link layer and forwards data frames based on MAC addresses. It learns where devices live on each port by reading source MACs and builds a MAC address table, so each frame is sent only to the appropriate port. This keeps local LAN traffic efficient and lets devices within the same network talk directly.

A router operates at the Network layer and moves packets between different networks using IP addresses. It examines the destination IP, consults routing tables and protocols to determine the best next hop, and forwards the packet toward its destination across multiple networks. Routers are what connect separate LANs or WANs and enable communication beyond a single local network.

That’s why the correct view is that switches handle frame forwarding within a LAN by MAC addresses, while routers route packets between networks using IP addresses. The other descriptions mix up the layers or the scope of each device’s function.