- A
Stop the RDS instance, then update the stack, then start it.
Why wrong: Incorrect: RDS instances cannot be stopped; they can only be rebooted.
- B
Add the 'AllowMajorVersionUpgrade' property to the DB instance in the template and update the stack.
Why wrong: Incorrect: That property is for version upgrades, not instance class changes.
- C
Modify the CloudFormation template to change the 'DBInstanceClass' property and set 'UpdateReplacePolicy' to 'Snapshot', then update the stack. This will create a new DB instance and delete the old one after taking a snapshot.
Correct: Forces replacement with snapshot preservation.
- D
Delete the CloudFormation stack, create a new stack with the new instance type, and restore from the automated backup.
Why wrong: Incorrect: Deleting the stack would delete the DB instance.
Quick Answer
The answer is to modify the CloudFormation template by changing the DBInstanceClass property and adding an UpdateReplacePolicy set to Snapshot, then update the stack. This is correct because the 'Cannot modify DB instance class' error occurs when CloudFormation attempts an in-place modification that RDS does not support for certain instance class changes, especially when automated backups are enabled; the service requires a full resource replacement rather than a simple update. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of CloudFormation's resource replacement behavior and the critical role of UpdateReplacePolicy in preserving data during stack updates. A common trap is assuming you can stop the RDS instance or manually modify it outside of CloudFormation, but the exam emphasizes that CloudFormation-driven replacements with snapshots are the safe, automated path. Memory tip: think "Replace to upgrade, snapshot to save" — when the class changes, CloudFormation must replace the resource, and the snapshot policy ensures no data loss.
DOP-C02 SDLC Automation Practice Question
This DOP-C02 practice question tests your understanding of sdlc automation. 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 uses AWS CloudFormation to manage infrastructure. They have a stack that creates an Amazon RDS DB instance with automated backups enabled. The DevOps team needs to modify the DB instance to use a larger instance type. They update the CloudFormation template and execute a stack update. The update fails with the error: 'Cannot modify DB instance class because the instance is in a state that does not allow modification.' The DB instance is in the 'available' state. The team needs to successfully update the instance type without data loss. What should the team do?
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
Modify the CloudFormation template to change the 'DBInstanceClass' property and set 'UpdateReplacePolicy' to 'Snapshot', then update the stack. This will create a new DB instance and delete the old one after taking a snapshot.
Option C is correct because modifying the DB instance class for RDS often requires a replacement (not just modification) when using CloudFormation, and a snapshot ensures data is preserved. Option A is wrong because stopping the instance is not allowed for RDS. Option B is wrong because deleting the stack would cause data loss. Option D is wrong because the error is not about lack of permissions.
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.
- ✗
Stop the RDS instance, then update the stack, then start it.
Why it's wrong here
Incorrect: RDS instances cannot be stopped; they can only be rebooted.
- ✗
Add the 'AllowMajorVersionUpgrade' property to the DB instance in the template and update the stack.
Why it's wrong here
Incorrect: That property is for version upgrades, not instance class changes.
- ✓
Modify the CloudFormation template to change the 'DBInstanceClass' property and set 'UpdateReplacePolicy' to 'Snapshot', then update the stack. This will create a new DB instance and delete the old one after taking a snapshot.
Why this is correct
Correct: Forces replacement with snapshot preservation.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Delete the CloudFormation stack, create a new stack with the new instance type, and restore from the automated backup.
Why it's wrong here
Incorrect: Deleting the stack would delete the DB instance.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- 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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which DOP-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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FAQ
Questions learners often ask
What does this DOP-C02 question test?
SDLC Automation — This question tests SDLC Automation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Modify the CloudFormation template to change the 'DBInstanceClass' property and set 'UpdateReplacePolicy' to 'Snapshot', then update the stack. This will create a new DB instance and delete the old one after taking a snapshot. — Option C is correct because modifying the DB instance class for RDS often requires a replacement (not just modification) when using CloudFormation, and a snapshot ensures data is preserved. Option A is wrong because stopping the instance is not allowed for RDS. Option B is wrong because deleting the stack would cause data loss. Option D is wrong because the error is not about lack of permissions.
What should I do if I get this DOP-C02 question wrong?
Identify which DOP-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 20, 2026
This DOP-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 DOP-C02 exam.
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