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Difficulty: MediumEnhancing Reliability and Disaster Recovery

An enterprise hosts a critical client-facing web application in the us-east-1 Region. The compute tier consists of a Java application running on Amazon EC2 instances inside private subnets, managed by an Auto Scaling group behind an Application Load Balancer (ALB). The storage tier consists of an Amazon RDS for PostgreSQL database in a Single-AZ deployment, and shared files are stored on an Amazon Elastic File System (Amazon EFS) file system. Outbound integrations for the application currently rely on a single NAT Gateway in us-east-1.

The enterprise wants to implement a disaster recovery (DR) solution in the us-west-2 Region using a warm standby strategy. The solution must achieve a Recovery Time Objective (RTO) of 30 minutes and a Recovery Point Objective (RPO) of 5 minutes. Additionally, the solutions architect must improve the reliability of outbound internet connections within the primary region to prevent single-point-of-failure events.

Which of the following combinations of actions should the solutions architect implement to meet these requirements? (Select TWO.)

  1. Deploy a NAT Gateway in each Availability Zone in the primary region's VPC, and configure the private subnet route tables to direct outbound traffic to the local NAT Gateway.Answer
  2. Enable Amazon EFS replication from us-east-1 to us-west-2, and provision an Amazon RDS for PostgreSQL cross-region read replica in us-west-2.Answer
  3. C
    Implement daily AWS Backup copy jobs to replicate RDS and EFS snapshots from us-east-1 to us-west-2, and script a recovery process using AWS Lambda.
  4. D
    Associate the Route 53 private hosted zone used for internal service resolution with the us-east-1 VPC, but delay associating it with the us-west-2 VPC until a failover event is initiated.
  5. E
    Retain the single NAT Gateway in us-east-1 and add a backup route pointing directly to the Internet Gateway in the private subnet route tables to handle outbound failover.

Answer

To meet the RTO and RPO requirements, the solutions architect must use Amazon EFS replication and a cross-region read replica for Amazon RDS. To eliminate the single point of failure for outbound internet traffic in the primary region, a NAT Gateway must be deployed in each Availability Zone.
Deploying a NAT Gateway in each Availability Zone ensures that an outage affecting one zone does not disrupt outbound internet connectivity for the remaining zones. Utilizing Amazon EFS replication and configuring an Amazon RDS cross-region read replica establishes continuous, low-latency replication that meets the recovery point objective of 5 minutes.

Step-by-Step Solution

1
Analyze primary region outbound reliability requirements.
Determine that deploying a single NAT Gateway introduces a single point of failure.
Designing for high availability requires deploying one NAT Gateway per Availability Zone to isolate failures.
2
Evaluate replication options for the storage and database tiers to achieve a 5-minute RPO.
Identify EFS replication and RDS cross-region read replicas as active replication mechanisms.
Asynchronous continuous replication satisfies the RPO requirement, whereas daily snapshot copies do not.
3
Verify dependency configurations such as Route 53 Private Hosted Zone associations.
Confirm that Private Hosted Zones must be pre-associated with both VPCs.
Pre-associating VPCs ensures seamless internal DNS resolution immediately upon disaster recovery failover.

Key Concept

Disaster Recovery implementation (RTO/RPO targets) and regional outbound connectivity high availability.
Estimated Time:3m 0s
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Topics

Enhancing Reliability and Disaster Recovery