SOA-C02 Cross-Region Read Replica Practice Question
A company wants to implement a disaster recovery solution for its on-premises database using AWS. The solution must have an RPO of less than 1 hour and an RTO of less than 4 hours. Which THREE steps should the SysOps administrator take? (Choose THREE.)
⚠ Common exam trap
Candidates often assume Multi-AZ (Option E) is a valid DR solution. However, Multi-AZ only provides high availability within a single Region, with synchronous replication and automatic failover. It does not protect against Region-wide outages or on-premises failures, and does not meet the cross-Region disaster recovery requirement implied by the need for an RPO < 1 hour and RTO < 4 hours for an on-premises database.
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
✓
Set up a cross-Region read replica for the RDS instance.
A cross-Region read replica for an RDS instance provides asynchronous replication to a secondary Region. After promoting the replica, the RTO can be under 4 hours, and the RPO is typically less than 1 hour. Option B is correct by launching an EC2 instance with the same database software and configuring continuous replication (e.g., log shipping or mirroring) from the on-premises database. This allows failover to the EC2 instance within the RPO and RTO targets. Option C is correct as AWS DMS can perform ongoing replication from the on-premises database to an RDS instance, meeting the RPO requirement with minimal data loss. Together, these steps form a multi-layered DR strategy: DMS for continuous replication, EC2 as a standby, and a cross-Region replica for regional resilience.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Set up a cross-Region read replica for the RDS instance.
Why this is correct
A cross-Region read replica creates a continuously updated, asynchronous replicate of an RDS database in a different AWS Region, with typical replication lag well under the 1-hour RPO. Promoting the replica makes it a standalone writable instance, a process that generally completes within minutes and satisfies the RTO. This is a solid DR approach, but it presupposes that the database is already running on RDS; for an on-premises source, you would need an initial migration into RDS before this option becomes viable.
- ✓
Launch an EC2 instance with the database software and configure replication.
Why this is correct
Correct: Launching an EC2 instance with the database software and configuring continuous replication (e.g., log shipping or database mirroring) from the on-premises database allows you to fail over to the EC2 instance within the RPO and RTO limits.
- ✓
Use AWS Database Migration Service (DMS) to replicate data to an RDS instance.
Why this is correct
Correct: AWS DMS can perform continuous replication from the on-premises database to an RDS instance, ensuring minimal data loss and meeting the RPO requirement. The RDS instance can then be used as a target for failover.
- ✗
Use AWS DataSync to sync the database files to Amazon S3.
Why it's wrong here
AWS DataSync is designed to transfer large volumes of files between on-premises storage and AWS, but it operates as a batch, file-based service rather than a continuous transaction-level replication engine. Copying raw database files to Amazon S3 with DataSync would not produce a transactionally consistent, ready-to-use database, and the sync interval would almost certainly exceed the required 1-hour RPO. Furthermore, restoring from S3 snapshots would add significant manual steps, failing the RTO of under 4 hours.
- ✗
Configure the RDS instance with Multi-AZ.
Why it's wrong here
Incorrect: Multi-AZ is a high-availability feature that provides automatic failover within a single AWS Region. It does not protect against Region failures or on-premises disasters, and therefore does not meet the disaster recovery requirements for the on-premises database.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
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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.