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Difficulty: MediumEnhancing Reliability and Disaster Recovery

A company operates a critical customer portal on AWS. The primary environment runs in the us-west-2 Region and consists of an Application Load Balancer (ALB) directing traffic to Amazon EC2 instances in an Auto Scaling group across three Availability Zones. The instances require internet access for external payment API calls, which is currently routed through a single NAT Gateway in one public subnet. The application uses a Route 53 Private Hosted Zone (PHZ) for internal service discovery. The database layer is an Amazon Aurora PostgreSQL Global Database with a primary cluster in us-west-2 and a read-only secondary cluster in us-east-1.

The company wants to enhance disaster recovery (DR) by implementing an active-passive cross-region strategy with a target recovery time objective (RTO) of 20 minutes and a recovery point objective (RPO) of 5 minutes. During a DR simulation, the operations team observes that outbound payment calls fail if the Availability Zone containing the NAT Gateway goes down, and internal service names do not resolve in the secondary Region after a manual failover.

Which combination of actions should a solutions architect recommend to resolve these issues and meet the DR objectives?

  1. A
    Deploy a NAT Gateway in each Availability Zone in us-west-2 and update the private subnet route tables. Associate the existing Route 53 Private Hosted Zone with the VPC in us-east-1. Configure Route 53 active-passive failover routing records using CNAME records pointing to the ALB DNS names, but do not configure or associate an external Route 53 health check, assuming Route 53 automatically detects the primary Region's endpoint status. In a disaster scenario, fail over the Aurora Global Database to us-east-1.
  2. B
    Deploy a NAT Gateway in each Availability Zone in us-west-2 and update the private subnet route tables. Create a new Route 53 Private Hosted Zone with the same domain name in us-east-1 and recreate all service discovery records. Configure Route 53 failover routing records for the public domain, associating the primary record with a Route 53 health check that monitors the primary ALB. In a disaster scenario, fail over the Aurora Global Database to us-east-1.
  3. Deploy a NAT Gateway in each Availability Zone in us-west-2 and update the private subnet route tables. Associate the existing Route 53 Private Hosted Zone with the VPC in us-east-1. Configure Route 53 failover routing records for the public domain, associating the primary record with a Route 53 health check that monitors the primary ALB. In a disaster scenario, fail over the Amazon Aurora Global Database to us-east-1.Answer
  4. D
    Maintain the single NAT Gateway in us-west-2 to control operational costs. Associate the existing Route 53 Private Hosted Zone with the VPC in us-east-1. Configure Route 53 failover routing records for the public domain, associating the primary record with a Route 53 health check that monitors the primary ALB. In a disaster scenario, restore the database in us-east-1 from the latest daily Amazon Aurora backup snapshot.

Answer

Deploy a NAT Gateway in each Availability Zone in the primary region, associate the existing Private Hosted Zone with the secondary VPC, configure Route 53 failover records with a primary health check, and fail over the Amazon Aurora Global Database.
The correct option correctly addresses all three identified resilience and DR issues: it provides high availability for outbound traffic by deploying a NAT Gateway per Availability Zone, ensures consistent internal service name resolution by associating the existing Private Hosted Zone with the secondary VPC, establishes automatic DNS redirection by using Route 53 failover routing with a health check, and preserves data consistency within RPO/RTO limits by utilizing Aurora Global Database failover capabilities.

Step-by-Step Solution

1
Ensure high availability for outbound traffic by deploying a NAT Gateway in each Availability Zone in us-west-2 and adjusting the private subnet route tables.
Outbound connectivity to the external payment API is resilient to Availability Zone outages.
Eliminating a single NAT Gateway removes a single point of failure for the application servers when accessing external endpoints.
2
Associate the existing Route 53 Private Hosted Zone with the secondary Region's VPC in us-east-1.
Internal DNS records are successfully resolved within the secondary VPC during a disaster recovery event.
Route 53 Private Hosted Zones must be explicitly associated with any VPCs that need to resolve the internal domain names.
3
Configure Route 53 failover routing for the public domain and create a Route 53 health check targeting the primary Application Load Balancer.
DNS requests are automatically routed to the secondary Region if the primary Region's endpoint becomes degraded.
Active-passive failover requires Route 53 health checks to detect primary endpoint failures and redirect traffic.
4
Initiate a failover of the Amazon Aurora Global Database to the us-east-1 cluster.
The secondary cluster is promoted to primary, allowing read/write operations to resume with minimal data loss.
Aurora Global Database replication is highly efficient, allowing promote/failover actions that meet strict RTO (20 minutes) and RPO (5 minutes) targets.

Key Concept

Disaster recovery failover coordination, multi-AZ outbound path redundancy, Private Hosted Zone VPC association, and global database promotion.
Estimated Time:2m 0s
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Topics

Enhancing Reliability and Disaster Recovery