300-410 Question 83
Single answerYou are troubleshooting an OSPFv2 adjacency issue between Router A and Router B. Both routers are in the same area and directly connected via Ethernet. The routers are configured with the correct IP addresses, and their OSPF process IDs match. However, the OSPF neighbors are stuck in the 'INIT' state. What is the most likely cause of the problem?
- A
The OSPF hello and dead timers are mismatched between Router A and Router B.
- B
The OSPF area type is mismatched between Router A and Router B.
- C
The network type on the Ethernet interface is set to 'point-to-point' instead of 'broadcast'.
- D
A Layer 2 issue is preventing communication between Router A and Router B.
Show answer and explanation
Correct answer: A
Explanation
The OSPF hello and dead timers must match between neighbors for an adjacency to form. In this scenario, the routers are stuck in the 'INIT' state, which suggests that Router A is receiving hello packets from Router B but is not responding due to the timer mismatch. This is the most likely cause of the problem.
- A. Correct.
If the OSPF hello and dead timers are mismatched, the routers will not form an adjacency and may remain in the 'INIT' state, as they fail to properly exchange hello packets.
- B. Incorrect.
An area type mismatch would typically result in the routers not forming any adjacency, but this does not explain the 'INIT' state specifically.
- C. Incorrect.
A point-to-point network type on Ethernet interfaces will not cause the 'INIT' state. OSPF still forms adjacencies regardless of the network type, unless there’s a deeper issue.
- D. Incorrect.
A Layer 2 issue would prevent any communication, but the 'INIT' state indicates that at least one router is receiving hello packets, so Layer 2 is working.