A public transit authority is designing a disaster recovery (DR) strategy for its new fare validation and ticketing API across two AWS Regions: us-east-1 (primary) and us-west-2 (secondary). The application runs on EC2 instances in private subnets behind an internal Application Load Balancer (ALB) and requires redundant outbound connectivity to transit gates via NAT Gateways. The database is Amazon Aurora PostgreSQL. The system has a Recovery Time Objective (RTO) of 15 minutes and a Recovery Point Objective (RPO) of 1 minute. Costs in the secondary region must be minimized during normal operations. The fare validation gates in both regions must resolve the internal endpoint api.transit.internal to their respective regional ALBs. Which of the following solutions meets these requirements?
- AConfigure Amazon Aurora cross-region DB cluster snapshots to be copied from us-east-1 to us-west-2 every hour. In the secondary VPC, deploy the application tier using an Auto Scaling group with a minimum capacity of 0, and deploy a single NAT Gateway to reduce idle gateway costs. Create a separate Route 53 Private Hosted Zone for transit.internal in each region's VPC independently without cross-VPC association. Configure Route 53 Failover routing records for api.transit.internal pointing to the regional Application Load Balancers.
- BSet up an Amazon Aurora DB cluster in us-east-1 with a cross-region Read Replica in us-west-2, and enable Aurora Auto Scaling to dynamically scale write capacity on the replica. In the secondary VPC, deploy the application tier using an Auto Scaling group with a minimum capacity of 1, and deploy redundant NAT Gateways across multiple Availability Zones. Create a single Route 53 Private Hosted Zone for transit.internal associated with both VPCs. Configure a Route 53 Geolocation routing policy for api.transit.internal to route write traffic to the nearest regional Application Load Balancer.
- Configure Amazon Aurora Global Database with the primary cluster in us-east-1 and a secondary cluster in us-west-2. In the secondary VPC, deploy the application tier using an Auto Scaling group configured with a minimum capacity of 1, and deploy redundant NAT Gateways across multiple Availability Zones. Create a single Route 53 Private Hosted Zone for transit.internal and associate it with the VPCs in both regions. Configure a Route 53 Failover routing policy for api.transit.internal that uses Route 53 health checks associated with CloudWatch alarms monitoring the primary ALB. During failover, promote the secondary Aurora cluster and scale up the Auto Scaling group in us-west-2.Answer
- DConfigure Amazon Aurora Global Database with the primary cluster in us-east-1 and a secondary cluster in us-west-2. In the secondary VPC, deploy the application tier using an Auto Scaling group configured with a minimum capacity of 1, and deploy a single NAT Gateway in one Availability Zone to minimize operational costs. Create a single Route 53 Private Hosted Zone for transit.internal and associate it with the VPCs in both regions. Configure Route 53 Failover routing records for api.transit.internal pointing to the Application Load Balancers with CloudWatch-based health checks.
Answer
Configure Amazon Aurora Global Database with the primary cluster in us-east-1 and a secondary cluster in us-west-2. In the secondary VPC, deploy the application tier using an Auto Scaling group configured with a minimum capacity of 1, and deploy redundant NAT Gateways across multiple Availability Zones. Create a single Route 53 Private Hosted Zone for transit.internal and associate it with the VPCs in both regions. Configure a Route 53 Failover routing policy for api.transit.internal that uses Route 53 health checks associated with CloudWatch alarms monitoring the primary ALB. During failover, promote the secondary Aurora cluster and scale up the Auto Scaling group in us-west-2.
The correct solution uses Amazon Aurora Global Database to achieve near-instantaneous cross-region replication, fitting the 1-minute RPO. The warm standby pattern (Auto Scaling group running at a minimum capacity of 1) keeps costs low while allowing the application to scale up rapidly within the 15-minute RTO during failover. Outbound high availability is maintained in the disaster recovery VPC by deploying NAT Gateways in multiple Availability Zones. Private DNS resolution for the shared domain name is achieved by creating a single Route 53 Private Hosted Zone and associating it with both VPCs, and a Route 53 Failover routing policy with health checks linked to CloudWatch alarms automates internal client-side redirection.
Step-by-Step Solution
Key Concept
Designing a cost-effective warm standby disaster recovery architecture with Route 53 private failover routing and Aurora Global Database replication.
Estimated Time:3m 0s