SAA-C03 Design Resilient Architectures Practice Question
A logistics company runs an order processing system on Amazon EC2 instances that read and write to an Amazon RDS for MySQL database. The database is currently a Single-AZ deployment. The company needs the database to survive an Availability Zone failure with automatic failover and minimal downtime. The application connects using a hardcoded DNS name. Which change should a solutions architect make?
⚠ Common exam trap
It's easy for candidates to confuse a read replica with a Multi-AZ standby; a read replica is asynchronous and does not provide automatic failover for writes.
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
✓
Convert the RDS for MySQL database to a Multi-AZ DB instance deployment and continue using the existing endpoint.
Converting the RDS for MySQL database to a Multi-AZ DB instance deployment creates a synchronous standby in a second Availability Zone and enables automatic failover. The database endpoint remains unchanged, so the application's hardcoded DNS name continues to work, satisfying the requirements for zone resilience and minimal downtime.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Convert the RDS for MySQL database to a Multi-AZ DB instance deployment and continue using the existing endpoint.
Why this is correct
Converting to a Multi-AZ DB instance deployment creates a synchronous standby in a different Availability Zone and provides automatic failover. The DNS endpoint remains the same, so the hardcoded connection string continues to work after failover. This meets the requirements for zone resilience and minimal downtime with the least application change.
- ✗
Enable automated backups with a longer retention period and restore the database to a new instance during a failure.
Why it's wrong here
Automated backups allow restoration to a point in time, but restoration creates a new database instance with a new endpoint and takes significant time. This does not provide automatic failover or minimal downtime. The application would also need to be reconfigured to use the new endpoint, which the scenario does not allow.
- ✗
Create a read replica in another Availability Zone and update the application to use the read replica endpoint for writes.
Why it's wrong here
A read replica is asynchronous and is intended for read scaling, not failover. It cannot accept writes while the primary is healthy, and promoting a read replica is a manual process that causes downtime. Updating the application to write to the read replica endpoint also requires code changes, which conflicts with the existing hardcoded DNS name.
- ✗
Migrate the database to Amazon DynamoDB with global tables enabled.
Why it's wrong here
Migrating from RDS for MySQL to DynamoDB requires a full data model redesign and application rewrite, which is not a minimal-downtime change. DynamoDB global tables provide multi-Region replication, but the scenario only requires Availability Zone resilience within one Region. This option introduces unnecessary complexity and cost.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
This SAA-C03 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 SAA-C03 exam.