What is the purpose of the default gateway in host networking?

• A. It provides the next hop to reach destinations outside the local subnet; the host uses it to forward non-local traffic.
• B. It assigns IP addresses to hosts.
• C. It blocks all external traffic.
• D. It acts as a DNS server.

Answer: (A)

The main idea is that a default gateway is the next hop for any traffic leaving the local network. A host can reach devices on its own subnet directly, but for anything outside that subnet, it sends the packet to the gateway’s address on the local network. The gateway router then takes care of forwarding the packet toward its destination across other networks. The host uses ARP to map the gateway’s IP to a MAC address on the local LAN, so it can actually send the packet to the gateway. The gateway’s role isn’t to assign IPs or to block everything by default, and it isn’t a DNS server. DHCP or manual configuration assigns IP addresses, and DNS translates names to addresses.