200-301 Question 314
Single answerA network administrator has configured a default route on a router using the command ip route 0.0.0.0 0.0.0.0 192.168.1.1. After completing the configuration, the administrator notices that the router is unable to forward packets to external networks. What could be a possible reason for this issue?
- A
The next-hop IP address 192.168.1.1 is unreachable.
- B
The default route command is missing the subnet mask.
- C
The router does not have a routing protocol enabled.
- D
The interface connected to the next-hop IP address is administratively down.
Show answer and explanation
Correct answer: A
Explanation
A default route is used to forward packets destined for unknown networks. The command ip route 0.0.0.0 0.0.0.0 192.168.1.1 specifies that packets should be forwarded to the next-hop IP address 192.168.1.1. If this next-hop IP address is unreachable, the router will fail to forward packets to external networks. Therefore, ensuring the next-hop IP address is reachable is critical for the default route to function correctly.
- A. Correct.
If the next-hop IP address (192.168.1.1) is unreachable, the router cannot forward packets to external networks as it cannot access the specified gateway. This is the correct answer.
- B. Incorrect.
The default route command is valid with a destination of 0.0.0.0 0.0.0.0 and does not require an additional subnet mask, so this is not the issue.
- C. Incorrect.
While a routing protocol can dynamically learn routes, it is not necessary when a static default route is configured. The absence of a routing protocol does not directly cause this problem.
- D. Incorrect.
If the interface connected to the next-hop IP address was administratively down, the router would notify the administrator of the issue. The question does not indicate this as a problem.