AWS Certified Solutions Architect Professional SAP-C02 Practice Question

The correct answer describes a classic warm standby architecture. In the DR region (us-west-2), a scaled-down but functional version of the application is running. This includes using an Amazon RDS cross-region read replica for asynchronous data replication, which is suitable for meeting a low RPO like 1 minute. A minimal Auto Scaling group (with a desired capacity of one) keeps the application tier running and ready to be scaled up quickly, which is a key characteristic of warm standby and essential for a 15-minute RTO. A small, single-node ElastiCache cluster is also provisioned to complete the minimal running environment. Upon failover, the RDS replica is promoted, the Auto Scaling group is scaled out, and Amazon Route 53 redirects traffic, all of which can be accomplished within the 15-minute RTO.

• The option suggesting deploying a new stack from AMIs and RDS snapshots describes a backup and restore strategy. This approach would have a much higher RTO and RPO, failing to meet the specified 15-minute RTO and 1-minute RPO.
• The option suggesting a fully scaled environment with latency-based routing describes a hot standby (or multi-site active/active) strategy. While it would meet the RTO/RPO, it is far more expensive than the required warm standby approach.
• The option suggesting an Auto Scaling group with a minimum capacity of zero describes a pilot light strategy, not a warm standby. A pilot light approach does not have servers running and ready to take traffic, which would make meeting a 15-minute RTO challenging.