350-401 Question 407
Single answerA network engineer is designing an OSPF network for a small branch office. The office network has a single router connected to the main office and does not require detailed route information about the rest of the corporate network. Which OSPF area type should the network engineer configure to minimize routing table size and prevent unnecessary external routes from being advertised into the branch office?
- A
Stub Area
- B
Totally Stubby Area
- C
Not-So-Stubby Area (NSSA)
- D
Backbone Area (Area 0)
Show answer and explanation
Correct answer: B
Explanation
A Totally Stubby Area is the optimal choice for a small branch office with a single router connected to the main office. It minimizes the routing table size by only allowing a default route, blocking both external (Type 5) LSAs and inter-area (Type 3) LSAs. This configuration simplifies routing and reduces overhead in scenarios where detailed route information is unnecessary.
- A. Incorrect.
A Stub Area reduces routing table entries by blocking external (Type 5) LSAs but still allows inter-area routes (Type 3 LSAs). This is not the most optimal choice for a small branch office that only needs a default route.
- B. Correct.
A Totally Stubby Area blocks both external (Type 5) LSAs and inter-area (Type 3) LSAs, only allowing a default route. This is the best choice for a small branch office that does not need detailed route information.
- C. Incorrect.
An NSSA allows limited external routes (Type 5 LSAs converted to Type 7 LSAs) into the area. This is used when the stub area itself needs to inject external routes, which is unnecessary for this scenario.
- D. Incorrect.
The Backbone Area (Area 0) is the core of an OSPF network and is not intended for branch offices or stub-like configurations. It is not suitable for minimizing routing table size in this context.