300-410 Question 20
Single answerYou have a network where OSPF and EIGRP are running on different parts of the network. Redistribution between OSPF and EIGRP has been configured on Router R1. However, some routes from OSPF are not appearing in the EIGRP routing table. Upon investigation, you find that the missing routes have administrative distances of 120. What could be the cause of this issue?
- A
The default metric for the redistributed OSPF routes into EIGRP is not configured.
- B
The redistributed OSPF routes are being filtered by an access control list (ACL).
- C
The OSPF routes are being redistributed with a higher administrative distance than EIGRP's external routes.
- D
The EIGRP topology table is full, preventing new routes from being added.
Show answer and explanation
Correct answer: A
Explanation
When redistributing routes between different routing protocols, such as OSPF into EIGRP, a seed metric is required for the routes to be considered in the receiving protocol's routing table. Without configuring a default metric, the routes will not appear in the EIGRP routing table.
- A. Correct.
EIGRP requires a seed metric for redistributed routes. Without a default metric, the OSPF routes will not be included in the EIGRP routing table.
- B. Incorrect.
While ACLs can filter routes during redistribution, there is no mention of an ACL being applied in this scenario. This is not the root cause.
- C. Incorrect.
The administrative distance of OSPF external routes (120) does not conflict with EIGRP external routes (170). This is not the issue here.
- D. Incorrect.
EIGRP does not have a specific limit that would prevent routes from being added to the topology table in this scenario. This is not the issue.