350-401 Question 155
Single answerA network engineer is tasked with implementing policy-based routing (PBR) on a router to ensure that specific traffic from the Sales department is routed through a dedicated WAN link, regardless of the destination. The engineer configures the following on the router:
- An access control list (ACL) to match traffic from the Sales department subnet.
- A route-map that references the ACL and sets the next-hop IP address of the dedicated WAN link.
- The route-map is applied to the inbound interface connected to the Sales department.
After the configuration, the Sales traffic is still using the default route instead of the dedicated WAN link. What is the most likely reason the policy-based routing is not working as intended?
- A
The ACL does not accurately match the Sales department traffic.
- B
The route-map is missing a permit statement for matching traffic.
- C
The route-map is applied to the wrong interface.
- D
The next-hop IP address in the route-map is unreachable.
Show answer and explanation
Correct answer: D
Explanation
Policy-based routing (PBR) requires that the next-hop IP address specified in the route-map is reachable. If it is not reachable, the router will fall back to the default routing table to forward the traffic. In this scenario, the most likely cause of the failure is that the next-hop IP address specified in the route-map is unreachable. Ensuring reachability of the next-hop IP address is critical for PBR to function as intended.
- A. Incorrect.
If the ACL does not accurately match the Sales department traffic, the route-map would not trigger for the traffic. However, this is unlikely since the question does not indicate an issue with the ACL configuration.
- B. Incorrect.
A route-map must include a permit statement to apply PBR to matching traffic. However, the question does not suggest that the route-map lacks a permit statement, so this is unlikely to be the issue.
- C. Incorrect.
If the route-map is applied to the wrong interface, policy-based routing would not impact the traffic. However, the question states that the route-map is applied correctly to the inbound interface connected to the Sales department.
- D. Correct.
If the next-hop IP address in the route-map is unreachable, PBR will fail and the default routing behavior will be applied. This is the most likely reason the Sales traffic is still using the default route.