In the OSI model, routing operates at which layer?

• A. Layer 3
• B. Layer 2
• C. Layer 4
• D. Layer 1

Answer: (A)

Routing decisions sit at the Network layer (Layer 3) of the OSI model. This layer handles logical addressing (like IP addresses) and the path selection needed to move packets between different networks. That’s exactly what routers do: examine the destination network, determine the best route, and forward packets toward their destination across multiple hops.

In contrast, Layer 2 (Data Link) is about local delivery within a single network segment using MAC addresses and switching. Layer 4 (Transport) deals with end-to-end communication, using ports and protocols such as TCP and UDP. Layer 1 (Physical) covers the actual signaling and transmission medium. Some devices can perform both switching and routing (multilayer devices), but routing as a function is fundamentally a Network layer activity.