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Difficulty: MediumMulti-AZ, Multi-Region Architectures and Disaster Recovery (DR)

A smart home IoT telemetry company runs its device monitoring platform in the us-east-1 Region. The database tier uses Amazon RDS for PostgreSQL. The compute tier runs on Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer. The company needs to design a disaster recovery (DR) plan in the us-west-2 Region. The design must achieve a Recovery Point Objective (RPO) of 5 minutes and a Recovery Time Objective (RTO) of 30 minutes, while keeping costs as low as possible. Which combination of actions should a solutions architect recommend to meet these requirements? (Select TWO.)

  1. Configure a cross-region read replica of the database in the secondary Region, and promote the replica to a standalone DB instance during a failover event.Answer
  2. Maintain a warm standby compute environment in the secondary Region with a scaled-down Auto Scaling group of EC2 instances, and scale it up to handle production traffic during a failover.Answer
  3. C
    Deploy an RDS Multi-AZ deployment across the primary and secondary Regions to provide synchronous database replication and automatic failover.
  4. D
    Configure Amazon Route 53 with latency-based routing to automatically route traffic to the secondary Region without configuring health checks.
  5. E
    Export PostgreSQL database backups to Amazon S3 Glacier Deep Archive every 5 minutes, and restore the database from the backup during a failover.

Answer

The correct combination of actions is to configure a cross-region read replica of the database in the secondary Region, promoting it to a standalone DB instance during failover, and to maintain a warm standby compute environment in the secondary Region with a scaled-down Auto Scaling group of EC2 instances, scaling it up to handle production traffic during failover.
The correct strategy combines a database cross-region read replica and a warm standby compute environment. The cross-region read replica replicates data asynchronously, meeting the 5-minute RPO, and can be promoted to primary within minutes. A warm standby compute tier runs at a minimal capacity to reduce costs, and can be scaled out within 30 minutes to satisfy the RTO.

Step-by-Step Solution

1
Analyze the disaster recovery objectives: RPO is 5 minutes, and RTO is 30 minutes.
The replication lag must be under 5 minutes, and the recovery process (database promotion and compute scaling) must take less than 30 minutes.
This establishes the boundaries for data replication and infrastructure restoration speed.
2
Select the database replication strategy.
An Amazon RDS cross-region read replica provides asynchronous replication with low lag (meeting RPO) and can be promoted quickly (meeting RTO). RDS Multi-AZ is rejected because it is limited to a single Region.
Choosing the database configuration that provides cross-region capabilities is necessary to meet both RPO and RTO constraints.
3
Select the compute recovery strategy.
A warm standby compute environment keeps a scaled-down Auto Scaling group running in the secondary Region, keeping costs low while allowing quick scale-up during failover to meet the RTO.
This ensures the compute capacity is ready to serve traffic within the 30-minute RTO window without incurring the full cost of an active-active setup.

Key Concept

Disaster recovery strategies differ in RTO, RPO, and cost. A warm standby approach combined with cross-region read replicas provides a cost-effective solution for low RTO and RPO requirements across AWS Regions.
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Topics

Multi-AZ, Multi-Region Architectures and Disaster Recovery (DR)

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