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Difficulty: HardHigh Availability and Disaster Recovery Design

A financial services company is designing a disaster recovery and high availability architecture for its new credit evaluation API. The workload is deployed across two AWS Regions: us-east-1 (primary) and us-west-2 (secondary). The application tier is deployed in private subnets and must query external credit bureaus via the internet. The database tier must use Amazon Aurora PostgreSQL. The business requires a Recovery Time Objective (RTO) of 10 minutes, a Recovery Point Objective (RPO) of 5 minutes, and consistent private DNS resolution for internal microservices across both VPCs. Which architecture meets these requirements with the highest availability and lowest administrative overhead?

  1. A
    Deploy Amazon Aurora PostgreSQL with Multi-AZ in us-east-1 and configure cross-region snapshot replication to us-west-2 every 4 hours. During a failover, restore the database from the latest snapshot, update Route 53 latency routing policies, and deploy a single NAT Gateway in each Availability Zone of both VPCs.
  2. B
    Deploy an Amazon Aurora PostgreSQL Global Database with the primary cluster in us-east-1 and a secondary cluster in us-west-2. Create a Route 53 Private Hosted Zone for internal DNS and associate it only with the us-east-1 VPC. Configure a Route 53 Failover routing policy with health checks pointing to the Application Load Balancers in both regions. Deploy NAT Gateways in multiple Availability Zones in both VPCs.
  3. Deploy an Amazon Aurora PostgreSQL Global Database with the primary cluster in us-east-1 and a secondary cluster in us-west-2. Create a Route 53 Private Hosted Zone for internal DNS and associate it with the VPCs in both regions. Configure a Route 53 Failover routing policy with health checks pointing to the Application Load Balancers in both regions. Deploy NAT Gateways in multiple Availability Zones in both VPCs.Answer
  4. D
    Deploy an Amazon Aurora PostgreSQL Global Database with the primary cluster in us-east-1 and a secondary cluster in us-west-2. Create a Route 53 Private Hosted Zone for internal DNS and associate it with the VPCs in both regions. Configure a Route 53 Failover routing policy with health checks pointing to the Application Load Balancers in both regions. Deploy a single NAT Gateway in a single public subnet in each region's VPC.

Answer

The architecture using Amazon Aurora PostgreSQL Global Database with multi-AZ NAT Gateways in both regions and a Route 53 Private Hosted Zone associated with both VPCs.
The configuration utilizing Amazon Aurora PostgreSQL Global Database, Route 53 Private Hosted Zones associated with both VPCs, Route 53 Active-Passive Failover with health checks, and multi-AZ NAT Gateways correctly addresses all RTO/RPO limits and avoids single points of failure.

Step-by-Step Solution

1
Evaluate the database replication strategy against RTO and RPO constraints.
Amazon Aurora PostgreSQL Global Database provides sub-second RPO and under 1 minute failover (RTO), whereas restoring from snapshots exceeds the 5-minute RPO and 10-minute RTO.
To ensure database recovery meets strict business SLAs.
2
Analyze private DNS resolution requirements for the multi-region workload.
The Route 53 Private Hosted Zone must be associated with the VPCs in both the primary and secondary regions.
Without cross-region association, microservices in the disaster recovery region VPC will fail to resolve internal service domains.
3
Assess outbound network egress configuration for high availability.
NAT Gateways must be deployed in multiple Availability Zones in each VPC.
A single NAT Gateway per VPC creates a single point of failure, violating high availability requirements if that specific zone experiences an outage.

Key Concept

Disaster recovery planning with tight RTO/RPO targets requires cross-region active-passive replication (like Aurora Global Database) combined with robust Route 53 failover health checks, multi-AZ VPC egress paths, and cross-region private hosted zone associations.
Estimated Time:3m 0s
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Topics

High Availability and Disaster Recovery Design

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