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Difficulty: HardHigh Availability and Disaster Recovery Design

A financial services company is designing a disaster recovery (DR) architecture for its critical transaction processing application. The application runs on Amazon Elastic Container Service (ECS) on AWS Fargate across two AWS Regions: us-east-1 (Primary) and us-west-2 (Secondary). The database layer uses Amazon Aurora PostgreSQL. The business requirements specify a Recovery Time Objective (RTO) of less than 5 minutes and a Recovery Point Objective (RPO) of less than 1 minute. Outbound transaction requests to external payment gateways must originate from a stable pool of static IP addresses. How should a solutions architect design the network and database layers to meet these requirements with high availability? (Select TWO.)

  1. Deploy an Amazon Aurora Global Database with the primary cluster in us-east-1 and a secondary cluster in us-west-2. Use Amazon Route 53 Application Recovery Controller (Route 53 ARC) routing controls to manage failover and route client traffic.Answer
  2. In both us-east-1 and us-west-2, deploy the ECS tasks across multiple Availability Zones (AZs). Deploy a dedicated NAT Gateway associated with an Elastic IP address in each AZ where tasks are deployed, and configure the private subnet route tables to use the local NAT Gateway in their respective AZ.Answer
  3. C
    In both us-east-1 and us-west-2, deploy the ECS tasks across multiple Availability Zones (AZs). To minimize NAT Gateway and Elastic IP costs, deploy a single NAT Gateway in the primary AZ of each region, and configure the private subnet route tables in all AZs to point to that single NAT Gateway.
  4. D
    Use AWS Backup to take hourly snapshots of the Aurora database in us-east-1 and copy them to us-west-2. During a failover event, restore the database from the copied snapshot in us-west-2 and spin up the ECS tasks.
  5. E
    For internal service discovery across regions, create a Route 53 Private Hosted Zone (PHZ) in the primary account and associate it with the us-east-1 VPC. Rely on cross-region VPC peering to automatically resolve names in the us-west-2 VPC without associating the PHZ to it.

Answer

Deploy an Amazon Aurora Global Database with the primary cluster in us-east-1 and a secondary cluster in us-west-2, using Route 53 ARC for failover. In both regions, deploy ECS tasks across multiple AZs using a dedicated NAT Gateway in each AZ to ensure multi-AZ redundancy and support the static IP requirement.
The correct options are the ones recommending Amazon Aurora Global Database combined with Route 53 Application Recovery Controller (Route 53 ARC) for fast, low-RPO/RTO database failover, and deploying a NAT Gateway in every Availability Zone in both regions. Aurora Global Database asynchronous replication keeps lag under a second, meeting the 1-minute RPO. Route 53 ARC routing controls allow failovers within minutes, meeting the 5-minute RTO. Deploying a NAT Gateway in each AZ ensures egress traffic has redundant paths and uses Elastic IP addresses to fulfill the static IP whitelisting requirement.

Step-by-Step Solution

1
Evaluate the database replication strategy to satisfy the RPO constraint of less than 1 minute.
Amazon Aurora Global Database provides sub-second cross-region replication, which easily satisfies the 1-minute RPO requirement, whereas snapshot backups fail this requirement.
Choosing the correct disaster recovery pattern is critical to meeting RTO and RPO requirements.
2
Determine the routing and failover orchestration mechanism to satisfy the RTO constraint of less than 5 minutes.
Using Route 53 Application Recovery Controller (Route 53 ARC) allows failover coordination and health monitoring, resulting in a database promotion and DNS change time of under 2 minutes, which is well within the 5-minute RTO.
Manual database restoration or poor DNS failover setups fail to meet the tight RTO.
3
Design the network egress configuration to provide static outbound IPs and ensure no single point of failure (SPOF) in the private subnets.
Deploying one NAT Gateway per Availability Zone ensures that if one zone fails, only the tasks in that zone are affected. Each NAT Gateway is assigned an Elastic IP, providing the required static IP pool for whitelisting.
Configuring private subnets in multiple AZs to use a single NAT Gateway introduces a single point of failure for internet access, violating high availability principles.

Key Concept

Designing multi-region disaster recovery for databases with sub-minute RPO using Amazon Aurora Global Databases, and ensuring high availability for outbound NAT traffic by avoiding cross-AZ dependencies and implementing redundant NAT Gateways.
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Topics

High Availability and Disaster Recovery Design

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