SOA-C02 Reliability and Business Continuity Practice Question
A SysOps administrator is designing a disaster recovery plan for a web application that runs on EC2 instances with data stored in an RDS MySQL database. The application requires a Recovery Point Objective (RPO) of 5 minutes and a Recovery Time Objective (RTO) of 1 hour. Which solution meets these requirements most cost-effectively?
⚠ Common exam trap
Test-takers frequently confuse Multi-AZ with cross-Region disaster recovery, assuming that a read replica in another Region is required for a 5-minute RPO, but Multi-AZ within a single Region with automated backups is sufficient and more cost-effective for the given RPO/RTO targets.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use RDS Multi-AZ with automated backups and EC2 AMI backups.
RDS Multi-AZ provides automatic synchronous replication to a standby instance in a different Availability Zone, ensuring minimal data loss and a fast failover that meets the 5-minute RPO and 1-hour RTO. Automated backups enable point-in-time recovery within the retention period, and EC2 AMI backups allow quick restoration of the application tier, making this the most cost-effective solution that satisfies both objectives without requiring cross-Region resources.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use a single RDS instance with daily snapshots and EC2 instance store.
Why it's wrong here
A single RDS instance with daily snapshots creates a single point of failure for the database tier, and daily snapshots provide a recovery point objective (RPO) of up to 24 hours, far exceeding the 5-minute RPO required. EC2 instance store is ephemeral, meaning data is lost if the instance stops, terminates, or suffers hardware failure; it is not a durable or recoverable storage option. This design lacks any automated failover or rapid recovery mechanism for the application tier, making it unsuitable for disaster recovery.
- ✗
Use EC2 Auto Scaling across Regions with an RDS standby instance.
Why it's wrong here
Configuring EC2 Auto Scaling across Regions requires duplicating the entire application stack and does not, by itself, replicate the database. An RDS standby instance is a Multi-AZ feature limited to a single region; it cannot be a cross-region standby, and the phrasing implies a manually managed or second RDS instance, which adds cost and operational overhead. Cross-region infrastructure is an unnecessarily expensive and complex solution when the target RTO is 1 hour and a within-region Multi-AZ failover combined with AMI backups can meet the objective with far less complexity.
- ✗
Use RDS Multi-AZ with read replicas in another Region.
Why it's wrong here
While RDS Multi-AZ provides automatic failover within a single region, it does nothing to replicate data to another region. Read replicas in another region replicate asynchronously and are intended for read scaling or manual promotion, not automatic disaster recovery; promoting a read replica requires manual intervention, which can easily exceed the 1-hour RTO. Additionally, asynchronous replication means the RPO is not guaranteed to meet a 5-minute target, and the two features operate independently rather than as an integrated failover solution.
- ✓
Use RDS Multi-AZ with automated backups and EC2 AMI backups.
Why this is correct
RDS Multi-AZ automatically fails over to a standby instance in a different Availability Zone within minutes, satisfying the 1-hour RTO for the database tier. Automated backups on RDS enable point-in-time recovery to any second within the backup retention period, achieving an RPO of approximately 5 minutes. EC2 AMI backups provide a consistent, restorable image of the application servers, allowing rapid relaunch of the compute tier. Together, these components form a practical, cost-effective disaster recovery plan that meets both the RPO and RTO targets without relying on ephemeral storage or manual cross-region promotion.
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Variation 1. A SysOps administrator is setting up a backup plan for an RDS MySQL database. The database is 500 GB in size and is used for a critical application. The company requires a Recovery Point Objective (RPO) of 5 minutes and a Recovery Time Objective (RTO) of 1 hour. Which solution meets these requirements?
easy- ✓ A.Deploy the RDS instance in a Multi-AZ configuration with automatic failover.
- B.Use AWS Backup to copy snapshots to a different AWS Region.
- C.Take manual snapshots every 5 minutes and store them in Amazon S3.
- D.Configure a cross-region read replica and promote it during failover.
Why A: Multi-AZ RDS with automatic failover meets the RPO of 5 minutes and RTO of 1 hour because it synchronously replicates data to a standby instance in a different Availability Zone. In the event of a failure, Amazon RDS automatically fails over to the standby, typically completing within 60–120 seconds, which satisfies the RTO. The synchronous replication ensures zero data loss (RPO of effectively 0), well within the 5-minute requirement.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SOA-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SOA-C02 exam.