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

A SaaS company provides a travel booking platform hosted in the us-east-1 Region. The architecture consists of Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer, and an Amazon RDS for PostgreSQL DB instance. The company wants to establish a disaster recovery (DR) site in the us-west-2 Region using a Warm Standby pattern. The DR solution must achieve a Recovery Time Objective (RTO) of 1515 minutes and a Recovery Point Objective (RPO) of 55 minutes, while minimizing ongoing costs.

Which TWO actions should a solutions architect take to meet these requirements? (Select TWO.)

  1. Deploy a scaled-down Auto Scaling group of EC2 instances and an Application Load Balancer in the secondary Region, and configure the Auto Scaling group to scale up in response to traffic during failover.Answer
  2. Create an Amazon RDS Cross-Region Read Replica in the secondary Region, and write a script to promote the replica to a primary DB instance in a disaster recovery event.Answer
  3. C
    Configure the Amazon RDS DB instance in Multi-AZ mode, selecting a subnet in the secondary Region as the standby zone to enable automatic cross-Region failover.
  4. D
    Configure an Amazon Route 53 latency-based routing policy to automatically redirect application traffic to the secondary Region during a primary Region outage.
  5. E
    Configure database backups to be stored in Amazon S3, transition them to S3 Glacier Deep Archive, and retrieve them in the secondary Region during failover.

Answer

The correct configurations are deploying a scaled-down Auto Scaling group of EC2 instances and an Application Load Balancer in the secondary Region (scaling up during failover) and creating an Amazon RDS Cross-Region Read Replica in the secondary Region (promoting it during failover).
To satisfy a 1515-minute RTO and 55-minute RPO under a Warm Standby pattern at a minimal cost, the solutions architect must maintain a running but scaled-down compute tier and configure active database replication. Deploying a scaled-down Auto Scaling group in the secondary Region ensures compute instances are already running and can immediately scale up to handle full traffic when a failover occurs, meeting the RTO. Creating an Amazon RDS Cross-Region Read Replica provides continuous, asynchronous replication to the secondary Region with a lag typically under a few minutes, meeting the RPO. In a failover scenario, this replica is promoted to a standalone primary database to accept write operations.

Step-by-Step Solution

1
Select a database replication technology that meets the RPO constraint.
An Amazon RDS Cross-Region Read Replica provides asynchronous replication to the secondary Region with very low replication lag, satisfying the 55-minute RPO.
Standard backups or snapshots cannot reliably meet a 55-minute RPO without significant cost, while synchronous Multi-AZ does not cross Regions.
2
Select a compute standby strategy that meets the RTO constraint at a minimal cost.
Deploying a scaled-down Auto Scaling group of EC2 instances in the secondary Region ensures compute instances are already running and can scale up quickly, satisfying the 1515-minute RTO.
A Pilot Light strategy (zero instances running) may take too long to bootstrap and pass health checks, failing the 1515-minute RTO. An active-active setup is too costly.
3
Establish failover automation for database promotion.
Create a script to promote the read replica to a primary standalone DB instance during failover.
Promotion changes the replica to a primary instance capable of accepting write operations in the recovery Region.

Key Concept

Disaster recovery strategies differ by Recovery Time Objective (RTO), Recovery Point Objective (RPO), and cost. A Warm Standby deployment maintains scaled-down but running compute resources in the recovery Region along with active database replication (such as a Cross-Region Read Replica) to support rapid recovery while minimizing idle resource costs.
Estimated Time:2m 0s
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Topics

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

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