In the TCP/IP model, which layer is responsible for routing data between networks?

• A. Network Interface Layer
• B. Network Layer
• C. Transport Layer
• D. Application Layer

Answer: (B)

Routing data between networks is handled by the Internet Layer in the TCP/IP model. This layer provides logical addressing with IP addresses and makes forwarding decisions to move packets from the source toward the destination across multiple routers. Routers operate at this layer, looking at the destination IP and using routing tables to pick the next hop. In contrast, the Network Interface (Link) Layer deals with delivering frames on a single local network using MAC addresses and doesn’t route between networks. The Transport Layer takes care of end-to-end data delivery (reliability with TCP or datagrams with UDP) but isn’t responsible for routing. The Application Layer hosts end-user processes and protocols, not routing. So, the Internet Layer is the part of TCP/IP that routes data between networks.