BFD is a bidirectional forwarding detection mechanism that can provide detection within seconds and achieve rapid detection of links. It can be used in conjunction with which of the following…

Question

Options

• ADual-machine hot tone
• BPolicy routing
• CBGP
• DStatic routing

• A
  100% (36)

Explanation

BFD is a protocol-agnostic failure detection tool - it operates at the forwarding plane and feeds failure signals up to whatever control-plane protocol is listening. Because it is not tied to any one protocol, virtually any routing or redundancy technology can subscribe to BFD sessions for fast failure notification.

• A (Dual-machine hot standby / VRRP-style redundancy): BFD accelerates failover detection between master and backup devices, replacing slow hello timers with sub-second link-state awareness.
• B (Policy routing): BFD can track the reachability of next-hops used in policy-based forwarding; when BFD declares a path down, the policy route can be withdrawn or rerouted immediately.
• C (BGP): BGP natively converges slowly (hold-down timer is typically 90 s); pairing it with BFD lets BGP react to link failures in milliseconds instead.
• D (Static routing): Static routes have no built-in failure detection; BFD fills that gap by monitoring the next-hop and triggering route removal when the path fails.

Since all four options are correct, there are no distractors here - the question tests whether you know BFD is protocol-agnostic.

Memory tip: Think of BFD as a universal smoke alarm - it doesn't care whether the room is labeled BGP, Static, Policy, or HA. Any protocol that needs fast failure notification can wire itself to the same alarm.

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