Which OSI/TCP/IP layer is routing?

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

Answer: (A)

Routing is about deciding the path packets take between different networks, using IP addresses to reach the final destination. That decision-making happens at the Network layer in the OSI model, and at the Internet layer in the TCP/IP model. Routers examine IP headers and routing tables to choose the next hop toward the destination, which is why this function sits at Layer 3.

Layer 2 handles local network addressing and switching within a single network segment (MAC addresses and frames). Layer 4 deals with end-to-end communication and ports (TCP/UDP) rather than path selection. Layer 1 is the physical transmission of signals. So routing across networks is a Layer 3 activity (Network/Internet layer).