300-440 Question 9
Single answerA network engineer observes that a router is selecting OSPF routes over EIGRP routes in the routing table, even though the EIGRP routes have a lower metric. Upon further investigation, the engineer determines that the administrative distance (AD) of EIGRP has been manually changed. What would be the most likely reason for OSPF routes being preferred over EIGRP routes in this scenario?
- A
The administrative distance of EIGRP was increased to a value higher than OSPF's default administrative distance.
- B
The OSPF routes are being redistributed into EIGRP, causing a conflict in route selection.
- C
The metric of the OSPF routes was manually adjusted to be lower than the EIGRP metric.
- D
The EIGRP process is in passive mode, preventing it from advertising its routes.
Show answer and explanation
Correct answer: A
Explanation
Administrative distance (AD) is a measure of the trustworthiness of a routing protocol's routes. Lower AD values are preferred over higher ones. By default, EIGRP has a lower AD (90) than OSPF (110), so EIGRP routes are typically preferred. However, if the AD of EIGRP is manually set to a value higher than 110, OSPF routes will be selected instead, even if the EIGRP routes have a better metric. This explains why OSPF is preferred in this scenario.
- A. Correct.
Correct. If the administrative distance of EIGRP is configured to a value higher than OSPF's default AD (110), the router will prefer OSPF routes over EIGRP, regardless of the metric.
- B. Incorrect.
Incorrect. Redistributing OSPF routes into EIGRP does not inherently impact the administrative distance of the routes. The issue described relates specifically to administrative distance, not route redistribution.
- C. Incorrect.
Incorrect. The metric determines the path selection within a protocol, but AD determines the preference between different routing protocols. This scenario is about administrative distance, not metric adjustments.
- D. Incorrect.
Incorrect. A passive EIGRP process would prevent it from forming neighbor adjacencies and advertising routes, but it does not explain the preference of OSPF routes in the routing table.