DOP-C02 Incident and Event Response Practice Question
A company uses AWS CloudFormation to deploy infrastructure. A recent stack update failed, and the engineer needs to roll back to the previous stable state. Which CloudFormation feature should the engineer use?
⚠ Common exam trap
Test-takers frequently confuse the 'Rollback' action with creating a Change Set or using Drift Detection, thinking they need to manually define the previous state, when in fact CloudFormation automatically preserves the previous stable state for rollback.
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 'Rollback' action in the CloudFormation console.
CloudFormation provides a built-in 'Rollback' action that automatically reverts a stack to its last known stable state when a stack update fails. This rollback occurs by default on failure, but if the engineer needs to manually trigger it after a failed update, they can use the 'Rollback' action in the CloudFormation console or API (e.g., `aws cloudformation rollback-stack`). This ensures the infrastructure returns to the previous working configuration without manual intervention.
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 AWS CloudFormation Drift Detection.
Why it's wrong here
AWS CloudFormation Drift Detection only compares the current state of the resources in a live stack against the originally declared template configuration, surfacing differences such as manual changes or resource replacement. It is a read-only audit operation that never modifies or rolls back infrastructure; after a failed update, it cannot revert resources to a previous healthy state, so it is not a rollback mechanism at all.
- ✗
Use AWS CloudFormation StackSets.
Why it's wrong here
AWS CloudFormation StackSets is an orchestration feature designed to manage identical stacks across multiple AWS accounts and Regions from a single declarative template, enabling consistent multi-account governance and scaled deployments. It does not provide any operation to revert a single stack's failed update in-place; even within a StackSet, rollback behavior for a member stack failure is handled by StackSet's own update options, not by a general-purpose 'Rollback' action, and the question refers to a standalone stack rollback.
- ✓
Use the 'Rollback' action in the CloudFormation console.
Why this is correct
The 'Rollback' action in the CloudFormation console is the correct approach because CloudFormation maintains an automatic rollback trigger for failed update operations, and when an update enters a failed state, you can explicitly invoke 'Rollback' from the console to restore the stack to its last known good template and parameter state. This action is specifically designed to undo the partial or failed changes, reverting affected AWS resources to their pre-update configuration, and is the direct rollback mechanism within CloudFormation's lifecycle.
- ✗
Create a Change Set and execute it.
Why it's wrong here
Creating and executing a Change Set is a forward-looking operation that lets you preview the effects of proposed stack changes before applying them; executing the Change Set performs the actual update, but if that update fails, the Change Set itself contains no logic for undoing the update. Change Sets are planning and execution tools, not recovery tools; they neither initiate a rollback nor revert resources, so while they help you anticipate drift or disruptive changes, they are not a substitute for CloudFormation's rollback functionality.
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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.