Implementing Cisco IP Routing (CCNP ROUTE, legacy) — Question 292

You have completed an OSPF implementation, and you are verifying OSPF operation. During this verification, you notice that the OSPF route of 172.16.10.0 is repeatedly appearing and disappearing from the routing table. Further investigation finds that the OSPF CPU utilization is very high and the routers are constantly performing SPF calculations. You determine that 172.16.20.2 is the source of the 172.16.10.0 route. Using the show ip ospf database router 172.16.20.1 command, you notice that when this show command is performed repeatedly, the contents of the LSA change every few seconds.
What could be the cause of this problem?

Answer options

• A. OSPF authentication errors between some of the routers.
• B. Two routers have the same OSPF router ID.
• C. Issues with mistuned OSPF timers.
• D. OSPF LSA pacing issues between some of the routers.

Correct answer: O, S, P, F

Explanation

The correct answer is D, as OSPF LSA pacing issues can lead to frequent route updates, causing the route to appear and disappear in the routing table. Other options like A and B would not directly cause the symptoms described, and C might cause issues but wouldn't specifically lead to the LSA changes observed.