RDS MySQL Multi-AZ: High Availability and Automatic Failover
A company is designing an Amazon RDS for MySQL database for an e-commerce application. Which TWO design strategies will help ensure high availability and automatic failover in the event of a primary instance failure?
Quick Answer
The correct answer is to enable Multi-AZ deployment for Amazon RDS MySQL. This is the right choice because Multi-AZ automatically provisions a synchronous standby replica in a different Availability Zone, ensuring that all writes are committed to both the primary and standby before a transaction is confirmed. In the event of a primary instance failure, Amazon RDS handles automatic failover by flipping the DNS record to the standby, typically completing the switch within one to two minutes with no data loss. On the AWS Certified Database Specialty DBS-C01 exam, this concept tests your understanding of high availability versus disaster recovery—a common trap is confusing Multi-AZ with read replicas, which are asynchronous and do not provide automatic failover. Remember: Multi-AZ is for high availability and automatic failover; read replicas are for read scaling. A useful memory tip is “Multi-AZ mirrors, read replicas steer.”
⚠ Common exam trap
It's easy for candidates to confuse read replicas (which are for read scaling and require manual promotion) with Multi-AZ standby replicas (which provide automatic failover), leading them to select options B or D incorrectly. Additionally, some candidates may overlook that using Amazon Aurora (option A) is a valid high-availability strategy for MySQL-compatible workloads.
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 Amazon Aurora instead of RDS MySQL.
Amazon Aurora is a MySQL-compatible database engine that provides built-in high availability and automatic failover across multiple Availability Zones, with up to 15 low-latency read replicas. Option C is correct because enabling Multi-AZ deployment for Amazon RDS MySQL provisions a synchronous standby replica in a different Availability Zone, and Amazon RDS automatically fails over to the standby in the event of a primary instance failure. Both strategies ensure automatic failover without manual intervention. Options B and D involve read replicas, which are for read scaling and require manual promotion for failover, not automatic. Option E (automatic backups) provides point-in-time recovery, not high availability or failover.
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 Amazon Aurora instead of RDS MySQL.
Why this is correct
Using Amazon Aurora instead of RDS MySQL provides built-in high availability with automatic failover across multiple Availability Zones, making it a valid design strategy.
- ✗
Create a read replica in the same Availability Zone.
Why it's wrong here
Creating a read replica in the same Availability Zone does not provide automatic failover; read replicas are for read scaling and require manual promotion.
- ✓
Enable Multi-AZ deployment.
Why this is correct
Enabling Multi-AZ deployment provisions a synchronous standby replica in a different AZ, enabling automatic failover with minimal downtime.
- ✗
Provision read replicas in different Availability Zones.
Why it's wrong here
Provisioning read replicas in different AZs still requires manual promotion for failover; it does not provide automatic high availability.
- ✗
Enable automatic backups.
Why it's wrong here
Enabling automatic backups ensures point-in-time recovery but does not provide automatic failover or high availability.
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Same concept, more angles
1 more way this is tested on DBS-C01
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 is running a critical application on Amazon RDS for Oracle. They need to ensure high availability with automatic failover in case of a database failure. The database size is 500 GB. Which solution should they implement?
medium- A.Create a cross-Region read replica
- B.Migrate to Amazon DynamoDB Global Tables
- C.Take regular snapshots and restore in a different Availability Zone
- ✓ D.Enable Multi-AZ deployment
Why D: Multi-AZ deployment for Amazon RDS for Oracle provides synchronous replication to a standby instance in a different Availability Zone, with automatic failover in the event of a database failure. This ensures high availability without manual intervention, meeting the requirement for automatic failover for a 500 GB Oracle database.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DBS-C01 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 DBS-C01 exam.