300-410 Question 81
Single answerA network engineer is troubleshooting an OSPFv2 adjacency issue between two routers, R1 and R2. Both routers are in the same area and have been correctly configured with matching OSPF process IDs and area IDs. However, the OSPF adjacency remains stuck in the 'INIT' state. What is the most likely cause of the issue?
- A
The OSPF hello and dead timers are mismatched between R1 and R2.
- B
The OSPF interface on R1 is configured as a passive interface.
- C
Authentication settings do not match between R1 and R2.
- D
The MTU settings on the interfaces of R1 and R2 do not match.
Show answer and explanation
Correct answer: A
Explanation
When OSPF adjacencies remain in the 'INIT' state, it often indicates that hello packets are being received, but there is a communication mismatch. A common cause is mismatched hello and dead timers between the two routers. Ensuring the timers match can resolve the issue and allow the adjacency to progress to the 'FULL' state.
- A. Correct.
Mismatched hello and dead timers can prevent an OSPF adjacency from forming, leaving it stuck in the 'INIT' state. This is the most likely cause when the adjacency does not progress beyond this state.
- B. Incorrect.
If an interface is set as passive, OSPF will not send hello packets on that interface, but it would not typically leave the adjacency in the 'INIT' state. Instead, it would prevent the adjacency from forming entirely.
- C. Incorrect.
Authentication mismatches would prevent the establishment of an OSPF adjacency, but they would typically leave the adjacency in the 'DOWN' state rather than 'INIT'.
- D. Incorrect.
MTU mismatches can cause OSPF adjacency issues, but they generally result in the adjacency being stuck in the 'EXSTART' or 'EXCHANGE' state, not the 'INIT' state.