300-410 · Question #85
What is an advantage of using BFD?
The correct answer is D. It has sub-second failure detection for layer 1 and layer 2 problems. BFD (Bidirectional Forwarding Detection) provides significantly faster detection of forwarding path failures compared to traditional mechanisms.
Question
Options
- AIt detects local link failure at layer 1 and updates routing table.
- BIt detects local link failure at layer 2 and updates routing protocols.
- CIt has sub-second failure detection for layer 1 and layer 3 problems.
- DIt has sub-second failure detection for layer 1 and layer 2 problems.
How the community answered
(31 responses)- B3% (1)
- C3% (1)
- D94% (29)
Why each option
BFD (Bidirectional Forwarding Detection) provides significantly faster detection of forwarding path failures compared to traditional mechanisms.
BFD is not limited to Layer 1 and informs routing *protocols* which then update routing tables, rather than updating the routing table directly; also, its key advantage is sub-second detection, which this choice omits.
While BFD detects Layer 2 failures and updates routing protocols, this choice misses its critical advantage of *sub-second* detection.
BFD does provide sub-second detection for Layer 1 and Layer 3 problems, but it is also highly effective in detecting Layer 2 forwarding path issues, making D a more comprehensive advantage.
BFD is designed to provide rapid, sub-second failure detection for various network issues, including physical link failures (Layer 1) and data link layer problems (Layer 2), as well as Layer 3 forwarding path issues. Its ability to quickly detect these failures across different layers is its primary advantage, allowing routing protocols to converge much faster.
Concept tested: BFD (Bidirectional Forwarding Detection) advantages
Source: https://www.cisco.com/c/en/us/td/docs/ios/iproute/configuration/guide/irp_bidirectional_forwarding_detection_psg_con_guide.html
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