300-420 Question 225
Single answerAn enterprise network is designed with dual routers at the branch site for redundancy, each connected to separate WAN links. During a failover test, you notice that when the primary router fails, traffic is not rerouted to the secondary router as expected. What is the most likely reason for this issue?
- A
The routing protocol does not support automatic failover.
- B
The failover timers on the secondary router are too long.
- C
The secondary router is not configured with the correct default route.
- D
The WAN link on the secondary router is not active.
Show answer and explanation
Correct answer: C
Explanation
Failover in a dual-router setup requires proper configuration of both routers to ensure seamless traffic rerouting. If the secondary router lacks the correct default route, it will not be able to forward traffic during a failover event, resulting in the observed issue. Proper route validation and redundancy testing should be part of the network design process.
- A. Incorrect.
This is incorrect because most modern enterprise routing protocols (e.g., OSPF, EIGRP, BGP) support failover. The issue is more likely due to a configuration problem.
- B. Incorrect.
While failover timers can impact how quickly failover occurs, they do not prevent failover entirely. The issue described suggests failover is not happening at all.
- C. Correct.
This is correct because if the secondary router is not configured with the correct default route, it will not know how to forward traffic during a failover event.
- D. Incorrect.
This could cause failover issues, but the question specifies that the failover test did not reroute traffic, which points to a misconfiguration rather than a physical link issue.