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Difficulty: MediumHigh Availability and Disaster Recovery Design

A SaaS company is designing a critical online booking application on AWS. The application must be deployed across two AWS Regions: us-east-1 (Primary) and us-west-2 (Secondary). The database layer requires a Recovery Point Objective (RPO) of less than 1 second and a Recovery Time Objective (RTO) of less than 1 minute. The application tier instances in both Regions need outbound internet access to communicate with external payment gateways, but they must remain private. The architecture must minimize single points of failure while optimizing for high availability.

Which two configuration options should the Solutions Architect implement to meet these requirements?

  1. Deploy an Amazon Aurora Global Database with the primary database cluster in us-east-1 and a secondary database cluster in us-west-2 to replicate data with typical latency of less than 1 second.Answer
  2. Provision a NAT Gateway in each Availability Zone utilized by the application in both us-east-1 and us-west-2, and configure Route 53 Failover routing records with health checks pointing to the Application Load Balancer in each Region.Answer
  3. C
    Deploy a single NAT Gateway in a single Availability Zone in each Region to route outbound internet traffic for the application tier, reducing hourly running costs.
  4. D
    Configure a multi-Region active-active configuration using Route 53 Weighted routing without health checks, relying on dynamic client-side DNS retries to route traffic away from a degraded Region.
  5. E
    Implement daily cross-Region Amazon Aurora database snapshot copies from us-east-1 to us-west-2, and configure an AWS Lambda function to automate snapshot restoration during a disaster event.

Answer

The Solutions Architect should implement Amazon Aurora Global Database for multi-region replication and deploy NAT Gateways in each Availability Zone alongside Route 53 Failover routing records with health checks.
To meet the RPO of less than 1 second and RTO of less than 1 minute, the database must use physical replication with sub-second latency. Amazon Aurora Global Database uses storage-level replication to achieve this. Promoting a secondary cluster takes less than a minute. For network high availability, deploying NAT Gateways in each Availability Zone avoids single points of failure. For multi-region DNS failover, Route 53 Failover records combined with active health checks are required to automatically redirect traffic to the standby Region during a primary Region outage.

Step-by-Step Solution

1
Select the database replication strategy that matches the recovery objectives.
Amazon Aurora Global Database is chosen because it replicates data storage-level across Regions under 1 second (RPO) and allows promotion in less than 1 minute (RTO).
Alternative methods such as cross-region snapshot copies have RPOs up to 24 hours and RTOs of several minutes or hours, which fail the targets.
2
Select the NAT Gateway design that satisfies the high availability requirement without single points of failure.
NAT Gateways are provisioned in each Availability Zone in both Regions.
A single NAT Gateway per Region introduces an AZ-level single point of failure, risking outbound connection drops for the entire Region if that AZ fails.
3
Select the DNS routing configuration for multi-region failover.
Route 53 Failover routing policy is configured with active health checks pointing to the ALBs.
Active health checks are necessary for Route 53 to automatically detect a regional endpoint outage and perform failover routing within the required RTO.

Key Concept

Multi-region high availability and disaster recovery design using Aurora Global Database storage replication, Route 53 active-passive DNS failover, and multi-AZ NAT gateway redundancy.
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Topics

High Availability and Disaster Recovery Design

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