AWS Certified Advanced Networking – Specialty (ANS-C01) — Question 46

A company's network engineer is designing an active-passive connection to AWS from two on-premises data centers. The company has set up AWS Direct Connect connections between the on-premises data centers and AWS. From each location, the company is using a transit VIF that connects to a Direct Connect gateway that is associated with a transit gateway.
The network engineer must ensure that traffic from AWS to the data centers is routed first to the primary data center. The traffic should be routed to the failover data center only in the case of an outage.
Which solution will meet these requirements?

Answer options

• A. Set the BGP community tag for all prefixes from the primary data center to 7224:7100. Set the BGP community tag for all prefixes from the failover data center to 7224:7300
• B. Set the BGP community tag for all prefixes from the primary data center to 7224:7300. Set the BGP community tag for all prefixes from the failover data center to 7224:7100
• C. Set the BGP community tag for all prefixes from the primary data center to 7224:9300. Set the BGP community tag for all prefixes from the failover data center to 7224:9100
• D. Set the BGP community tag for all prefixes from the primary data center to 7224:9100. Set the BGP community tag for all prefixes from the failover data center to 7224:9300

Correct answer: B

Explanation

The correct answer is B because it sets a higher preference for the primary data center by tagging its prefixes with a lower community value (7224:7300), which will be preferred by the routing policy. Options A, C, and D incorrectly assign tags that would either prioritize the failover data center or create an undesirable routing preference, failing to meet the requirement of directing traffic primarily to the primary data center.