300-440 Question 15
Single answerA network engineer is troubleshooting a route map applied to an OSPF process to filter specific routes. The route map is configured as follows:
route-map FILTER_ROUTES deny 10
match ip address ACL_FILTER
route-map FILTER_ROUTES permit 20
router ospf 100
redistribute eigrp 1 route-map FILTER_ROUTES
The access-list 'ACL_FILTER' is configured to match the prefix 192.168.10.0/24. However, during verification, the engineer notices that the 192.168.10.0/24 route is still present in the OSPF database. What is the most likely cause of this issue?
- A
The access-list 'ACL_FILTER' is incorrectly defined and does not match any prefixes.
- B
The route-map FILTER_ROUTES does not have a 'permit' statement for the 192.168.10.0/24 prefix.
- C
The route-map FILTER_ROUTES is missing a 'match' clause in the permit sequence.
- D
The 'redistribute eigrp 1' command is not using the correct route-map.
- E
The deny statement in the route map prevents the route from being redistributed, but it does not remove it from the OSPF database.
Show answer and explanation
Correct answer: E
Explanation
The deny statement in the route map prevents the redistribution of the 192.168.10.0/24 prefix into OSPF. However, if the route was already present in the OSPF database (e.g., learned through normal OSPF operations or another redistribution process), the deny statement does not remove it. Route maps control redistribution but do not influence routes already in the OSPF database unless combined with additional mechanisms like filtering at the OSPF process level.
- A. Incorrect.
If the access-list was incorrectly defined, the route-map would not match any prefixes. However, per the configuration, the ACL correctly matches the 192.168.10.0/24 prefix.
- B. Incorrect.
A 'permit' statement in a route map allows matched prefixes to be redistributed. However, the issue here is not related to permitting redistribution but understanding the behavior of the deny statement.
- C. Incorrect.
A 'match' clause is already present in the deny sequence of the route map, so this is not the cause of the issue.
- D. Incorrect.
The 'redistribute eigrp 1' command correctly references the FILTER_ROUTES route-map, so this is not the issue.
- E. Correct.
The deny statement in the route map prevents the route from being redistributed into OSPF, but it does not actively remove the route from the OSPF database if it was learned through other means. This is the correct answer.