DOP-C02 Configuration Management and IaC Practice Question
A company manages its infrastructure using AWS CloudFormation. They have a production stack that includes an Amazon RDS Multi-AZ DB instance. The stack was created using the 'aws cloudformation create-stack' command with default settings. The DB instance uses a custom DB parameter group. A DevOps engineer needs to modify a parameter in the DB parameter group and update the stack. The engineer updates the template to change the parameter value and runs 'aws cloudformation update-stack'. The update fails with a 'ROLLBACK_IN_PROGRESS' status. The engineer checks the CloudFormation console and sees that the DB instance was successfully modified, but the stack is rolling back. The rollback fails because the DB instance cannot be reverted to the original parameter value. The stack is now in 'UPDATE_ROLLBACK_FAILED' state. What should the engineer do to resolve this situation and apply the desired parameter change?
⚠ Common exam trap
It's easy for candidates to think manual reversion or stack deletion is required, but CloudFormation provides a built-in recovery mechanism (`continue-update-rollback`) that avoids downtime and data loss.
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 the 'aws cloudformation continue-update-rollback' command with the '--resources-to-skip' parameter to skip the DB instance, allowing the stack to reach 'UPDATE_ROLLBACK_COMPLETE'. Then apply a change set with the desired parameter change.
When a CloudFormation stack is in UPDATE_ROLLBACK_FAILED state, the `continue-update-rollback` command with `--resources-to-skip` allows you to skip the resource that cannot be rolled back (the RDS DB instance with the custom parameter group). This moves the stack to UPDATE_ROLLBACK_COMPLETE, after which you can apply a change set with the desired parameter change. This approach avoids manual intervention or stack deletion while preserving the modified DB instance.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Run 'aws cloudformation update-stack' again with the original template to revert the changes.
Why it's wrong here
CloudFormation rejects any update-stack request while the stack is in the UPDATE_ROLLBACK_FAILED state, so resubmitting the original template will not be accepted. The stack must first move to a stable state such as UPDATE_ROLLBACK_COMPLETE via continue-update-rollback, or be deleted. Since the original template only reverses the parameter change, it does not address the underlying failure that caused the rollback to fail, making it an invalid recovery action.
- ✓
Use the 'aws cloudformation continue-update-rollback' command with the '--resources-to-skip' parameter to skip the DB instance, allowing the stack to reach 'UPDATE_ROLLBACK_COMPLETE'. Then apply a change set with the desired parameter change.
Why this is correct
The continue-update-rollback command is the designed mechanism to recover from a failed rollback. By specifying --resources-to-skip, you tell CloudFormation to ignore the RDS DB instance that is blocking the rollback, allowing the stack to transition to UPDATE_ROLLBACK_COMPLETE. Once stable, you can use a change set to reapply the desired parameter change in a controlled, reversible way, ensuring the stack's template and live resources are aligned.
- ✗
Revert the parameter value manually in the RDS console and then resume the rollback.
Why it's wrong here
Manually changing the RDS parameter value in the console may fix the database's runtime behavior, but CloudFormation's stack state is still marked as UPDATE_ROLLBACK_FAILED because the stack's template and record of the last update were not changed. Attempting to resume the rollback after the manual fix is unsupported and may cause the rollback to re-attempt the same failing resource. The correct approach is to use continue-update-rollback with resources-to-skip, which gives CloudFormation an explicit way to bypass the problematic resource without requiring manual, out-of-band modifications.
- ✗
Delete the stack and recreate it with the updated template.
Why it's wrong here
Deleting the stack and recreating it is a highly disruptive action that can result in data loss for the Multi-AZ DB instance, especially if you haven't configured DeletionPolicy or a final DB snapshot; CloudFormation's default deletion behavior removes the database. It also ignores the stack's existing state and forces a full rebuild, increasing downtime significantly. Even in a production incident, this is a last resort, not a recommended recovery from UPDATE_ROLLBACK_FAILED, because CloudFormation provides a non-destructive recovery path.
Visual reference
Go deeper
Related to this question
About these practice questions
One of 1,298 original DOP-C02 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.