AWS Certified Solutions Architect Professional SAP-C02 Practice Question

The correct approach is to use a combination of Weighted and Latency routing policies. A top-level Weighted routing policy splits the traffic according to the specified percentages. The Latency routing policy, nested under the main weight, directs users to the endpoint with the lowest latency and manages failover by removing unhealthy endpoints from DNS responses.

• Correct Answer: The solution involves creating a top-level Weighted routing policy. One record, with a weight of 5, directs 5% of traffic to the ap-southeast-1 ALB for A/B testing. The other record, with a weight of 95, points to a separate set of Latency-based records. These Latency records point to the ALBs in us-east-1 and eu-west-1. By associating health checks with these Latency alias records and setting "Evaluate Target Health" to Yes, Route 53 will automatically stop routing traffic to any region that becomes unhealthy, thus providing failover to the other healthy, low-latency region.

• Incorrect Answer (Latency-based only): Using only a Latency-based policy for all three regions would not guarantee that ap-southeast-1 receives exactly 5% of the traffic. Traffic distribution would depend entirely on which users are geographically closest to that region.

• Incorrect Answer (Failover and Geoproximity): A standard Failover routing policy is for active-passive setups and does not consider latency for the active endpoint. Geoproximity routing is for shifting traffic based on the physical distance between users and resources and is less precise for percentage-based splitting than a Weighted policy.

• Incorrect Answer (Multivalue Answer): A Multivalue Answer routing policy returns up to eight healthy records in a random order, letting the client choose. It does not perform latency-based routing and cannot be layered with a Weighted policy in the manner described to meet the requirements.