SOA-C02 Reliability and Business Continuity Practice Question
A company runs a critical database workload on an Amazon RDS for MySQL DB instance with Multi-AZ deployment in the us-east-1 region. The SysOps administrator must design a disaster recovery strategy that can recover from a complete regional outage. The Recovery Time Objective (RTO) is 2 hours and the Recovery Point Objective (RPO) is 1 hour. Which solution meets these requirements at the lowest cost?
⚠ Common exam trap
Many candidates choose Option B (automated backups) because they assume backups can be restored cross-Region, but automated backups are Region-specific and do not support cross-Region restore without additional snapshot copy configuration, which is not mentioned in the option.
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
✓
Create a cross-Region read replica in another Region and promote it to a standalone DB instance during a disaster.
A cross-Region read replica continuously replicates data from the primary RDS MySQL instance to another Region with minimal lag, typically achieving an RPO of seconds to minutes, well within the 1-hour requirement. Promoting the replica to a standalone instance during a disaster can be done in minutes, meeting the 2-hour RTO. This approach is the lowest cost among the viable options as it uses existing replication infrastructure without additional data transfer fees for snapshots or DMS replication instances.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Create manual snapshots of the DB instance every hour and copy them to another AWS Region.
Why it's wrong here
Manual snapshots are taken at intervals; copying to another Region adds delay. This approach cannot guarantee an RPO of 1 hour because the snapshot schedule may miss the window, and recovery requires creating a new instance from the snapshot which can take longer than 2 hours.
- ✗
Enable automated backups with a retention period of 35 days and restore to a different Region when needed.
Why it's wrong here
Automated backups are stored only in the same Region. You would need to copy them manually, and the RPO is at least the backup window (usually 24 hours for automated backups), exceeding the 1-hour RPO.
- ✓
Create a cross-Region read replica in another Region and promote it to a standalone DB instance during a disaster.
Why this is correct
A cross-Region read replica provides continuous asynchronous replication with low lag (typically seconds). In a disaster, promoting the replica to a primary instance takes only minutes, meeting the RTO and RPO requirements with minimal cost.
- ✗
Use AWS Database Migration Service (DMS) to continuously replicate data to a DB instance in another Region.
Why it's wrong here
AWS Database Migration Service (DMS) is not suitable for achieving the specified 2-hour RTO and 1-hour RPO for a critical database workload recovering from a regional outage. DMS introduces replication latency and requires significant manual intervention for failover, making it challenging to meet such strict recovery objectives reliably. This option is tempting as it offers continuous cross-Region data replication. However, DMS is primarily designed for database migrations, including heterogeneous ones, or for creating read replicas where the recovery time and point objectives are less stringent, offering flexibility across database engines.
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Same concept, more angles
1 more way this is tested on SOA-C02
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company has an Amazon RDS for PostgreSQL DB instance with Multi-AZ deployment in us-east-1. The SysOps administrator must design a disaster recovery strategy to recover from a regional outage. The Recovery Time Objective (RTO) is 1 hour and the Recovery Point Objective (RPO) is 5 minutes. Which solution meets these requirements at the lowest cost?
hard- ✓ A.Create a Read Replica in a different region and promote it during a disaster.
- B.Take daily snapshots and copy them to another region.
- C.Use cross-region automated backups.
- D.Deploy a second Multi-AZ DB instance in another region.
Why A: A cross-region Read Replica meets the RPO of 5 minutes because replication is continuous (asynchronous) with minimal lag, and the RTO of 1 hour is achievable by promoting the replica during a disaster. This is the lowest-cost option because it uses a single standby instance in another region without the overhead of a full Multi-AZ deployment or frequent snapshot transfers.
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.