AWS Certified Advanced Networking – Specialty (ANS-C01) — Question 36

A company has deployed a software-defined WAN (SD-WAN) solution to interconnect all of its offices. The company is migrating workloads to AWS and needs to extend its SD-WAN solution to support connectivity to these workloads.
A network engineer plans to deploy AWS Transit Gateway Connect and two SD-WAN virtual appliances to provide this connectivity. According to company policies, only a single SD-WAN virtual appliance can handle traffic from AWS workloads at a given time.
How should the network engineer configure routing to meet these requirements?

Answer options

• A. Add a static default route in the transit gateway route table to point to the secondary SD-WAN virtual appliance. Add routes that are more specific to point to the primary SD-WAN virtual appliance.
• B. Configure the BGP community tag 7224:7300 on the primary SD-WAN virtual appliance for BGP routes toward the transit gateway.
• C. Configure the AS_PATH prepend attribute on the secondary SD-WAN virtual appliance for BGP routes toward the transit gateway.
• D. Disable equal-cost multi-path (ECMP) routing on the transit gateway for Transit Gateway Connect.

Correct answer: C

Explanation

The correct answer is C because configuring the AS_PATH prepend on the secondary SD-WAN virtual appliance ensures that BGP prefers the primary SD-WAN appliance for routing traffic from AWS workloads. Options A and B do not effectively prioritize the primary appliance for AWS traffic, while option D does not address the requirement of directing traffic through a single SD-WAN appliance.