In the OSI model, at which layer does a router primarily operate to forward packets between networks?

• A. Network
• B. Physical
• C. Data Link
• D. Transport

Answer: (A)

Routers operate at the Network layer, where the key job is moving data between different networks. They inspect the destination IP address in each packet and use routing tables to decide the next hop toward the destination. This layer provides logical addressing and path selection, which is exactly what a router does when connecting multiple networks—finding the best route and forwarding the packet along that path.

The other layers don’t handle inter-network routing: the Physical layer is about the actual transmission of raw bits over a medium; the Data Link layer (which includes switches) forwards frames within a single local network using MAC addresses; the Transport layer deals with end-to-end data delivery, reliability, and port numbers, not routing decisions.