DBS-C01 Question #65: Real Exam Question with Answer & Explanation

Question

A Database Specialist is planning to create a read replica of an existing Amazon RDS for MySQL Multi-AZ DB instance. When using the AWS Management Console to conduct this task, the Database Specialist discovers that the source RDS DB instance does not appear in the read replica source selection box, so the read replica cannot be created. What is the most likely reason for this?

Options

• AThe source DB instance has to be converted to Single-AZ first to create a read replica from it.
• BEnhanced Monitoring is not enabled on the source DB instance.
• CThe minor MySQL version in the source DB instance does not support read replicas.
• DAutomated backups are not enabled on the source DB instance.

Explanation

Explanation

Automated backups must be enabled on the source RDS DB instance (retention period set to at least 1 day) before a read replica can be created - this is a hard prerequisite enforced by AWS, which is why the instance doesn't appear in the console's source selection box. Option A is incorrect because Multi-AZ and read replicas are fully compatible and can coexist; there is no requirement to convert to Single-AZ first. Option B is incorrect because Enhanced Monitoring is a performance observability feature and has no bearing on whether read replicas can be created. Option C is incorrect because all currently supported minor versions of MySQL on RDS support read replicas, making this an implausible scenario.

Memory Tip: Think of automated backups as the "foundation" - AWS uses the binary logs (enabled through automated backups) to replicate changes to read replicas. No backups = No binary logs = No read replica. A quick way to remember: "You can't read what was never written down."

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