300-410 Question 34
Single answerA network engineer is tasked with implementing Policy-Based Routing (PBR) on a Cisco router to ensure that HTTP traffic sourced from the 10.1.1.0/24 network is routed through a specific next-hop address (192.168.1.1), regardless of the routing table. After configuring the necessary route map and applying it to the interface, the engineer notices that the policy is not being applied. What could be the reason for this issue?
- A
The route map does not have a 'match' statement to identify HTTP traffic.
- B
The ACL used in the route map is incorrectly permitting all traffic.
- C
The next-hop address specified in the route map is not reachable.
- D
Policy-Based Routing is not supported on the configured interface.
Show answer and explanation
Correct answer: C
Explanation
Policy-Based Routing requires that the next-hop address specified in the route map be reachable. If the next-hop is unreachable, the router will revert to traditional routing based on the routing table, effectively bypassing the policy. This scenario highlights the importance of verifying the reachability of the next-hop address when troubleshooting PBR issues.
- A. Incorrect.
The 'match' statement is necessary to identify HTTP traffic, but if it was missing, no traffic would be selected for PBR. However, the scenario indicates that the policy is configured but not being applied, which points to a different issue.
- B. Incorrect.
An ACL permitting all traffic would still allow Policy-Based Routing to function, although it would route all traffic instead of just HTTP traffic. This does not explain why the policy is not being applied.
- C. Correct.
If the next-hop address (192.168.1.1) specified in the route map is not reachable, PBR will not function because the router cannot forward traffic to an unreachable next-hop. This is the most likely reason for the issue.
- D. Incorrect.
Policy-Based Routing is supported on most modern Cisco interfaces. Unless explicitly stated in the scenario, this is unlikely to be the issue.