350-401 Question 148
Select 3You are tasked with configuring an OSPF network in a multi-area environment. The network consists of Area 0 (backbone), Area 1, and Area 2. Summarization is required to reduce the size of the routing table between areas. Additionally, the network includes point-to-point links and broadcast segments, and you need to ensure OSPF neighbor adjacencies form correctly. Which of the following configurations would meet the requirements?
- A
Configure manual summarization on the Area Border Routers (ABRs) to aggregate routes between areas.
- B
Set the OSPF network type to 'point-to-point' on all interfaces, regardless of the actual topology.
- C
Use the 'passive-interface' command on interfaces where OSPF adjacencies are not required.
- D
Enable default summarization on all OSPF routers to simplify the configuration.
- E
Ensure that OSPF hello and dead timers are consistent on all OSPF interfaces within their respective network types.
Show answer and explanation
Correct answers: A, C, E
Explanation
To configure a simple OSPF environment with multiple areas, it is essential to use summarization on ABRs to reduce routing table size, apply the 'passive-interface' command to disable unnecessary OSPF adjacencies, and ensure consistent hello and dead timers to maintain neighbor adjacencies. These configurations help optimize OSPF performance and ensure proper operation in a multi-area environment.
- A. Correct.
Correct: Summarization on ABRs reduces the size of the routing table by advertising a single summary route instead of multiple specific routes.
- B. Incorrect.
Incorrect: Setting the network type to 'point-to-point' on all interfaces is not appropriate as it can cause issues with broadcast networks and misconfiguration.
- C. Correct.
Correct: The 'passive-interface' command prevents OSPF from forming unnecessary adjacencies on interfaces where routing updates are not needed, improving security and performance.
- D. Incorrect.
Incorrect: Default summarization is not applicable in OSPF as it is specific to protocols like EIGRP. OSPF requires manual summarization on ABRs.
- E. Correct.
Correct: Consistent hello and dead timers are required for OSPF neighbor adjacencies to form successfully. Mismatched timers can prevent adjacency formation.