R1 has correctly configured EIGRP to filter routes using a route map named question. The
configuration that follows shows the entire route map and related configuration. Which of the
following is true regarding the filtering action on prefix 10.10.10.0/24 in this case?
route-map question deny 10
match ip address 1
route-map question permit 20
match ip address prefix-list fred
!
access-list 1 deny 10.10.10.0 0.0.0.255
ip prefix-list fred permit 10.10.10.0/23 le 25

A.
It will be filtered due to the deny action in route map clause 10.

B.
It will be allowed because of the double negative (two deny references) in clause 10.

C.
It will be permitted due to matching clause 20’s reference to prefix-list freD.

D.
It will be filtered due to matching the implied deny all route map clause at the end of the
route map.

Explanation:
When used for route filtering, the route map action (permit or deny) defines the

filtering action, and any referenced match commands’ permit or deny action just defines
whether the prefix is matcheD. By not matching ACL 1 with a permit action,
EIGRP does not consider a match to have occurred with clause 10, so it moves to
clause 20. The prefix list referenced in clause 20 has a permit action, matching prefixes
from 10.10.10.0–10.10.11.255, with prefix lengths from 23–25. Both criteria
match the prefix in question, making answer C correct.