Exam AWS Certified Advanced Networking - Specialty ANS-C01 topic 1 question 146 discussion

Asynchronous BFD is automatically turned on for all AWS Direct Connect interfaces on the AWS side. You can't configure BFD settings on the AWS side. When creating a BFD session, the BFD protocol always selects the longer and slower timer.

Configuring Bidirectional Forwarding Detection (BFD) on the Direct Connect connections on the on-premises router will provide the largest reduction in the BGP failover time. BFD is a protocol that enables rapid detection of link or session failures, allowing for faster convergence and faster traffic rerouting. By configuring BFD on the on-premises router, the company can reduce the failover time from minutes to seconds, improving the resiliency of their critical VPC workloads that connect to the on-premises data center through the redundant active-passive AWS Direct Connect connections.

You can configure Bidirectional Forwarding Detection (BFD) on your network. Asynchronous BFD is automatically enabled for each AWS Direct Connect virtual interface. It's automatically enabled for Direct Connect virtual interfaces, but does not take effect until you configure it on your router.

D is correct

agreed - D

it's D. https://docs.aws.amazon.com/directconnect/latest/UserGuide/Welcome.html By enabling BFD on both sides of the Direct Connect connection, you can reduce the BGP failover time from minutes to seconds. BFD allows the BGP neighbor relationship to be quickly torn down when a failure is detected on the Direct Connect connection. Otherwise, by default, BGP waits for three keep-alives to fail at a hold-down time of 90 seconds.