300-440 Question 80
Single answerA network engineer is troubleshooting an OSPFv2 adjacency issue between two routers, R1 and R2. The routers are directly connected, and their interfaces are configured with IP addresses in the same subnet. However, the OSPF adjacency is stuck in the 'INIT' state. What is the most likely cause of this problem?
- A
The OSPF hello and dead timers are mismatched between R1 and R2.
- B
The OSPF process IDs on R1 and R2 do not match.
- C
The OSPF network type on the interfaces is set to 'point-to-multipoint'.
- D
The OSPF area IDs configured on R1 and R2 are different.
Show answer and explanation
Correct answer: A
Explanation
In OSPF, the 'INIT' state means a router has received a hello packet from its neighbor but has not seen its own Router ID in the hello packet's neighbor list. This commonly occurs when there is a mismatch in OSPF hello and dead timers between the two routers. Other factors, such as area ID mismatches, would prevent the routers from progressing to the 'INIT' state altogether.
- A. Correct.
This is the correct answer. A mismatch in OSPF hello and dead timers between two routers prevents them from forming an adjacency. The 'INIT' state indicates that one router is receiving hello packets from the other but cannot establish a bidirectional communication due to such a mismatch.
- B. Incorrect.
This is incorrect. OSPF process IDs are locally significant and do not need to match between routers for adjacency formation.
- C. Incorrect.
This is incorrect. A 'point-to-multipoint' network type does not prevent adjacency formation. It affects how OSPF treats the network but is unrelated to the adjacency issue described.
- D. Incorrect.
This is incorrect. If OSPF area IDs are different, the routers will not form an adjacency and will not even reach the 'INIT' state.