350-401 Question 403
Single answerA network administrator is configuring OSPF for a remote branch office with limited connectivity. The branch office network will only require a single default route to reach external destinations, and it does not need to maintain a full OSPF database. Which OSPF feature should the administrator implement on the branch office router to meet these requirements?
- A
Configure the branch office router as an OSPF stub area
- B
Configure the branch office router as an OSPF totally stubby area
- C
Configure the branch office router as an OSPF not-so-stubby area (NSSA)
- D
Configure the branch office router with OSPF area range summarization
Show answer and explanation
Correct answer: B
Explanation
In the given scenario, the branch office requires a minimal OSPF configuration that reduces the routing table size and prevents unnecessary route advertisements. Configuring the branch office router as a totally stubby area satisfies these requirements by blocking both external and inter-area LSAs, injecting only a default route into the area. This approach optimizes resource usage and simplifies the OSPF configuration for the branch office.
- A. Incorrect.
This option refers to a stub area, which reduces the size of the OSPF database by blocking external LSAs (Type 5). However, it still allows inter-area routes (Type 3 LSAs), which is not ideal for a branch office with limited connectivity.
- B. Correct.
A totally stubby area blocks both external (Type 5) and inter-area (Type 3) LSAs, injecting only a default route into the area. This is the best choice for a branch office requiring minimal routing information.
- C. Incorrect.
An NSSA allows external routes (Type 7 LSAs) to be advertised from the branch office into the OSPF domain. This is unnecessary and inefficient for the given scenario, as the branch office only needs a default route.
- D. Incorrect.
OSPF area range summarization is used for summarizing routes between areas, which is not relevant in this case as the branch office does not need detailed inter-area or external route information.