Implementing Cisco Enterprise Advanced Routing and Services (ENARSI) — Question 330

Routers R1 and R2 have been configured to use Bidirectional Forwarding Detection? What is the advantage of doing this?

Answer options

• A. It is able to discover local link failures at layer 1 and provide automatic re-routing
• B. It is able to discover local link failures at layer 1 and provide automatic re-routing
• C. It is able to discover local link failures at layer 1 only and provides detection for this in less than one second.
• D. It is able to discover local link failures at layers 1 and 2 and provides detection for this in less than one second.

Correct answer: D

Explanation

The correct answer is D because Bidirectional Forwarding Detection detects failures at both layer 1 and layer 2, ensuring rapid failover in less than one second. Options A and B, while correct in mentioning detection of layer 1 failures, do not encompass layer 2 capabilities. Option C incorrectly limits detection to layer 1 only, missing the broader functionality provided by BFD.