AWS Certified CloudOps Engineer Associate SOA-C03 Practice Question

A company runs its e-commerce app in two AWS Regions. Each Region has an ALB fronting EC2 instances. The business wants active-passive failover: traffic must go to the standby Region only when the primary Region is unreachable. Operations require DNS health checks to query HTTPS /health on the app, not the ALB default check. Which solution provides this failover with minimal operational overhead?

Deploy AWS Global Accelerator with both ALBs as endpoints and assign all traffic weight to the primary Region; rely on the accelerator's built-in health checks for failover.
Create weighted DNS records (100 and 0) for the two ALBs and use a script to update the weights based on a periodic curl /health test.
Create two CNAME records in Route 53 that use the failover routing policy, each pointing to the DNS name of its Region's ALB. Attach an HTTPS health check that calls /health to the primary record and leave the secondary record without a health check.
Create two latency-based alias A records that point to each Region's ALB and enable Evaluate Target Health on both records.

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Answer Description

Failover routing in Amazon Route 53 lets you create a primary and a secondary record. The primary record is associated with an HTTPS health check that can be configured to request a specific path such as /health. When that health check fails, Route 53 automatically stops returning the primary record and returns the secondary record instead, sending traffic to the standby Region. Because the records are CNAMEs that reference the ALB DNS names, you can attach the custom health check. Alias records pointing to an ALB cannot have custom Route 53 health checks associated with them; they can only use 'Evaluate Target Health,' which does not check a specific path. A scripted approach has higher operational overhead. While AWS Global Accelerator also provides health-based failover and allows custom health check paths, it is a more complex service designed for improving global application performance and is not the most direct or minimal solution for this specific DNS failover requirement. Latency-based routing would distribute traffic to both Regions instead of maintaining an active-passive posture.

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