The correct answer is to manually promote the read replica to a standalone DB instance. This is required because Amazon RDS for MySQL does not support automatic failover for read replicas; unlike a Multi-AZ deployment, a read replica is designed for read scaling and disaster recovery but remains a passive copy that must be explicitly promoted to become writable. On the AWS Certified Data Engineer Associate DEA-C01 exam, this question tests your understanding of the distinction between Multi-AZ automatic failover and manual read replica promotion—a common trap is assuming RDS handles the transition automatically. Remember that after promotion, the old replica becomes a new standalone instance, and you must manually update application connection strings, as RDS does not redirect traffic. A helpful memory tip: “Read replicas are readers, not automatic leaders—you must promote to demote the failure.”
DEA-C01 Data Store Management Practice Question
This DEA-C01 practice question tests your understanding of data store management. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company has an Amazon RDS for MySQL DB instance with read replicas. The primary DB instance fails. What is the correct procedure to promote a read replica to become the new primary?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "primary"
Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Manually promote the read replica to a standalone DB instance.
When an Amazon RDS for MySQL primary DB instance fails, read replicas do not automatically become the new primary. The correct procedure is to manually promote the read replica using the AWS Management Console, CLI, or API, which converts it into a standalone DB instance. After promotion, you must update your application endpoints to point to the new primary, as RDS does not handle this automatically.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Modify the read replica to be a Multi-AZ deployment and failover will occur.
Why it's wrong here
Modifying to Multi-AZ does not promote the replica; it creates a standby in another AZ.
✗
RDS automatically fails over to the read replica within 5 minutes.
Why it's wrong here
RDS does not automatically fail over to a read replica; you must manually promote.
✓
Manually promote the read replica to a standalone DB instance.
Why this is correct
This is the correct procedure to make the read replica the new primary.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Delete the primary and the read replica will automatically become the primary.
Why it's wrong here
Deleting the primary does not promote the replica; the replica remains a replica.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse read replicas with Multi-AZ standby instances, assuming automatic failover applies to both, but RDS read replicas require manual promotion and do not provide automatic failover.
Detailed technical explanation
How to think about this question
Under the hood, an RDS read replica uses MySQL's asynchronous replication (based on binary log positions or GTIDs) to stay current with the primary. During promotion, RDS stops replication and applies any remaining relay logs, then transitions the instance to read-write mode. A subtle behavior is that if the read replica is lagging behind the primary at the time of failure, you may lose transactions that were not yet replicated, so monitoring replication lag is critical in production.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Data Store Management — This question tests Data Store Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Manually promote the read replica to a standalone DB instance. — When an Amazon RDS for MySQL primary DB instance fails, read replicas do not automatically become the new primary. The correct procedure is to manually promote the read replica using the AWS Management Console, CLI, or API, which converts it into a standalone DB instance. After promotion, you must update your application endpoints to point to the new primary, as RDS does not handle this automatically.
What should I do if I get this DEA-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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