What is the primary purpose of using a default route in a stub network?

• A. To provide a single exit path to reach all non-local destinations with minimal routing state.
• B. To advertise all possible routes to every neighbor.
• C. To increase routing table size by listing all networks.
• D. To isolate the network from the internet.

Answer: (A)

A default route acts as a single exit path for destinations that aren’t covered by more specific routes. In a stub network, there is just one uplink to reach the rest of the Internet or other networks, so directing all unknown destinations to that single next hop minimizes routing state—you don’t need numerous specific routes or frequent updates. This keeps the router simple, reduces memory and processing load, and still provides access to all non-local destinations through that one gateway. The other options would either increase routing state, try to advertise every route, or unnecessarily isolate the network from outside connectivity, which isn’t the goal of a default route in a stub network.