300-420 · Question #308
300-420 Question #308: Real Exam Question with Answer & Explanation
The correct answer is B: - The core layer must advertise a default route toward the aggregation layer.. To hide network instability, reduce overhead, and conserve memory in a hierarchical campus design, the core layer should advertise a default route towards the aggregation layer.
Question
Refer to the exhibit. An architect is designing a Layer 3 campus network. The design must hide network instability, reduce network overhead, and conserve critical device memory. Which route summarization solution must the architect select?
Options
- A- The aggregation layer must advertise a default route toward the core layer.
- B- The core layer must advertise a default route toward the aggregation layer.
- C- The aggregation layer must advertise a default route toward the access layer.
- D- The core layer must advertise a default route toward the aggregation layer.
Explanation
To hide network instability, reduce overhead, and conserve memory in a hierarchical campus design, the core layer should advertise a default route towards the aggregation layer.
Common mistakes.
- A. The aggregation layer advertising a default route to the core layer is incorrect; the core layer typically needs to know all reachable networks or have its own default to external providers.
- C. While the aggregation layer typically advertises a default route to the access layer to reduce routing tables on access devices, this option addresses a narrower scope and does not comprehensively fulfill the requirements for the overall campus network design regarding the core-aggregation interaction.
- D. This option is identical to B and therefore correct; if presented as separate choices, it would indicate a redundant option in the question.
Concept tested. Hierarchical network summarization and default routing
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