What is the primary purpose of a default route in a router's forwarding table?

• A. To forward packets whose destination is not found in any specific route to a next-hop gateway.
• B. To advertise routes to neighbors
• C. To block traffic to non-local networks
• D. To prioritize local network traffic

Answer: (A)

Packets that don’t have a more specific path in the routing table are sent through the default route, which acts as a catch-all to a next-hop gateway (0.0.0.0/0 for IPv4, ::/0 for IPv6). This setup lets a router reach destinations beyond its known networks by forwarding those undefined destinations to an upstream router or internet gateway. The router uses the longest-prefix match rule, so only when no longer, specific route exists will the default route be chosen. Without a default route, unknown destinations could be dropped or would require many individual static routes. The other options describe different network behaviors—advertising routes is done by routing protocols, blocking traffic is the job of firewalls/ACLs, and prioritizing traffic is about QoS, not the default path.