What is the role of a default gateway in an IP network?

• A. It is the router interface that connects a host's local network to other networks and forwards traffic destined for non-local addresses.
• B. It assigns IP addresses to hosts.
• C. It acts as a firewall for the network.
• D. It converts MAC addresses to IP addresses.

Answer: (A)

The main idea is that the default gateway acts as the exit point for a device to reach networks outside its local subnet. Each host uses the gateway’s local IP as its gateway address. When a device wants to reach a destination outside its own network, it sends the packet to this gateway. The gateway then uses its routing table to forward the packet toward the destination, possibly through several routers, until it reaches the correct network. The term “default” means this path is used whenever there isn’t a more specific route for the destination.

A quick context: to send to the gateway on the local network, the host first uses ARP to learn the gateway’s MAC address, then forwards the frame to that MAC. While a gateway can include firewall features, its essential role in this question is as the router interface that connects the local network to other networks and forwards non-local traffic. The other options don’t fit this primary function: assigning IP addresses is done by DHCP, firewall duties are separate features, and ARP is the mechanism that maps MAC addresses to IP addresses, not the gateway’s main role.