You have implemented mutual route redistribution between OSPF and EIGRP on a border router. When
checking the routing table on one of the OSPF routers within the OSPF routing domain, you are seeing some,but not all of the expected routes. Which two things should you verify to troubleshoot this problem? (Choose two.)
A. The border router is using a proper seed metric for OSPF.
B. The border router is using a proper seed metric for EIGRP.
C. The administrative distance is set for OSPF and EIGRP.
D. The missing EIGRP routes are present in the routing table of the border router.
E. The subnet keyword on the border router in the redistribute EIGRP command.
Correct Answer: DE
We are checking the routing table on EIGRP routers not OSPF so we don’t need to check the seed metric for OSPF. Besides OSPF doesn’t need to specify seed metric as all external routes get a default metric of 20
(except for BGP, which is 1) -> A is not correct.
We must specify seed metrics when redistributing into EIGRP (and RIP). If not all the redistributed routes will
not be seen but the question says only some routes are missing -> B is not correct.
The default administrative distance for external routes redistributed into EIGRP is 170 so we don’t need to set it -> C is not correct.
We should check the routing table of the border router to see the missing OSPF routes are there or not. An
incorrect distribute-list can block some routes and we can’t see it in other EIGRP routers -> D is correct.
Answer D is obvious that we should check all the routes we want to redistribute are present in the routing table of the border router. Let’s discuss about answer E.
A rule of thumb when redistributing into OSPF is we should always include the “subnets” keyword after the
redistributed route. For example:
router ospf 1
redistribute eigrp 100 subnets
This keyword makes sure all of the routes, including subnets are redistributed correctly into OSPF. For example these routes are learned via EIGRP:
Then without the keyword “subnets”, only 192.168.1.0/24 network is redistributed into OSPF.