Refer to the exhibit. Router R2 should be learning the route for 10.123.187.0/24 via EIGRP. Which action resolves the issue without introducing more issues?
A.
Redistribute the route in EIGRP with metric, delay, and reliability.
B.
Use distribute-list to modify the route as an internal EIGRP route.
C.
Use distribute-list to filter the external routes in OSPF.
D.
Remove route redistribution in R2 for this route in OSPF.
My assumption: the route 10.123.187.0/24 could be a static route which is redistributed into eigrp, and so it gets the AD 170 as eigrp external route.
The the route goes to R2 where all eigrp routes are redistributed into ospf as E2 external ospf routes.
At this point, the route 10.123.187.0/24 has an AD 110 in ospf and an AD 170 in eigrp on R2, thus ospf wins, and R2 learns the route from ospf.
We would need to stop the EIGRP route (10.123.187.0/24) from getting redistributed into OSPF using a route-map, which means solution "D".
Some good examples with different solutions:
https://learningnetwork.cisco.com/s/question/0D56e0000B7yzCVCQY/filtering-of-prefix-into-out-of-both-eigrp-and-ospf
https://community.cisco.com/t5/other-network-architecture-subjects/redistribution-from-eigrp-to-ospf/td-p/290844
C. Use distribute-list to filter the external routes in OSPF. --> Do we really want to filter all routes??? Introduce more issues.
D. Remove route redistribution in R2 for this route in OSPF. --> We filter this route. Less chance to introduce issues.
Answer = D
D is correct, if we do not want to redistribute a certain route we can create a prefix list or an ACL with the permit statetment, and then create a route-map, the first sequence will match the prefix list or the acl with the deny statetment and the second sequence can just be a permit.
With this route-map you are just saying which route will be redistributed, the route-map will negate the redistribution of that particular prefix, but first remember the permit statement in the acl/prefix list is mandatory because "we permit that prefix to be denied" this is the logic of a route-map
Fizzer is right!
Reading carefully and more carefully again the answer is saying remove route redistribution in R2 for this route in OSPF, BUT this CANNOT be possible.
The router itself is not doing redistribution otherwise it will not get the ospf route.
So there is another router doing redistribution and in this case the only thing that we can do is filtering even if in this case they are forcing us to filter other routes.
C is the right answer, D is not actually possible because even if this was a RIP learned route on R2 with AD of 120, redistributing RIP into OSPF on R2 will not remove the RIP route from the routing table and install the now External OSPF route because OSPF has AD of 110.
it does makes sense when you think about it, because RIP would be the primary protocol that learned the route on R2, and redistributing it into OSPF on this same router does not make OSPF the boss over the route
Also if you look closely, OSPF learned about the route from 10.1.3.2 which is probably where the redistribution happened whereas EIGRP learned it from 10.1.2.2 who probably also did the redistribution
Sorry team I was wrong in the previous answer, analyzing the question well. The correct response is C and not D, because D is receiving the route and redistribution is not removed. The most certain thing is that the network in EIGRP has AD higher than the AD of external routes of OSPF.
Tested in lab filter external ospf route and put EIGRP route
Since R2 is receiving the routes as "O E2" routes, he can't be the router that is redistributing them into OSPF, so D is not correct (he would see the routes as the original protocol). I think the EIGRP route to 10.123.187.0/24 is an external route and so we need to lower the AD.
I think answer B is correct:
https://community.cisco.com/t5/routing/eigrp-fd-is-inaccessible-when-re-distribution/td-p/1497303
However, i can't find a way to do this in a route map. Does anyone know if this is possible? If it's not possible, C is the only valid option, but as other have said, this will create other issues since 2 other routes will also be removed. Changing the AD of "D EX" routes would be a better option but it's not in any answer.
Also, if you do B without route filtering, it would cause new problems (loop). So the best option might actually be C here...
I'm going for D
the question say Which action resolves the issue" without introducing more issues"
if filter the external routes in OSPF -> might delete other O E2 route??
so... I think is D
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