Which mechanism can you use to achieve sub-second failover for link failure detection when a
switched Ethernet media is used and loss of signal is not supported by the link provider?

A.
OSPF standard hellos

B.
Cisco Discovery Protocol link detection

C.
Bidirectional Forwarding Detection

D.
Fast Link Pulse

E.
autonegotiation

Explanation:
BFD is a detection protocol designed to provide fast forwarding path failure detection times for all
media types, encapsulations, topologies, and routing protocols. In addition to fast forwarding path
failure detection, BFD provides a consistent failure detection method for network administrators.

Because the network administrator can use BFD to detect forwarding path failures at a uniform
rate, rather than the variable rates for different routing protocol hello mechanisms, network
profiling and planning will be easier, and reconvergence time will be consistent and predictable