SOA-C03 Practice Exam Questions | AWS Certified Associate

Comprehensive and Detailed Explanation From Exact Extract of AWS CloudOps Documents:

The requirement is classic active-passive (production in us-east-1, DR in us-west-2 “only for failover”). The most operationally efficient and purpose-built solution is Route 53 failover routing combined with health checks. With failover routing, Route 53 designates one record as PRIMARY (us-east-1) and another as SECONDARY (us-west-2). Route 53 continuously evaluates the health check associated with the primary endpoint (commonly the ALB DNS name or a specific health-check path). If the primary fails, Route 53 automatically returns the secondary record, directing client DNS resolution to the DR region. This ensures us-west-2 is used only when us-east-1 is unhealthy, directly matching the requirement.

Latency routing (Option B) is designed to route users to the region with the lowest latency, which can actively send traffic to us-west-2 even when us-east-1 is healthy—violating the “DR only” constraint. Options C and D introduce custom automation (CloudWatch + Lambda + DNS record updates) that increases operational overhead, adds failure modes, and is unnecessary because Route 53 already provides managed health-check-based failover. Additionally, “EC2 instance terminated” is not a reliable proxy for full application availability, and DNS modification automation is more complex than using native Route 53 failover policies.