DOP-C02 Resilient Cloud Solutions Practice Question
A company uses AWS CloudFormation to deploy infrastructure. During a recent deployment, the stack failed to create an Amazon RDS DB instance because of a parameter validation error. The DevOps engineer fixed the parameter and wants to resume the stack creation without recreating the resources that were already successfully created. The stack template is parameterized and uses nested stacks. What is the MOST efficient way to resume the stack creation?
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 CloudFormation stack update operation with the corrected parameter.
CloudFormation stack updates can be used to fix the issue. By updating the stack with the corrected parameters, CloudFormation will only modify the failed resource and not recreate already created resources.
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 the CloudFormation stack update operation with the corrected parameter.
Why this is correct
Calling the UpdateStack API (or the update operation in the console) on a stack in CREATE_FAILED state is the correct recovery path. CloudFormation only re-evaluates the resources that depend on the changed parameter, so the failed RDS instance is created while already-created resources remain untouched and no downtime is introduced. Any other approach either destroys existing resources or is not applicable to a creation failure.
- ✗
Manually create the RDS instance with the corrected parameter and update the stack to import it.
Why it's wrong here
Manually creating the RDS instance and importing it does not facilitate resuming the stack's failed creation. CloudFormation's resource import feature is designed to bring *existing, unmanaged resources* under stack control, or to re-associate resources previously retained from a deleted stack. This option is tempting as it *does* allow CloudFormation to manage the resource, but it bypasses the stack's declarative creation process, which the engineer wishes to resume. The stack is in a failed state, not awaiting an import operation.
- ✗
Delete the entire stack and redeploy with the corrected parameter.
Why it's wrong here
Deleting a CREATE_FAILED stack and redeploying is disproportionate: it tears down every successfully provisioned resource (EC2, security groups, VPC components, etc.) and then recreates them from scratch, which can take substantial time and risk data loss if a database was already created and left behind. CloudFormation's DeleteStack will also attempt to delete any non-retained resources, so the rollback cost is high. For a simple parameter correction, this only causes unnecessary downtime and should be avoided.
- ✗
Use the 'ContinueUpdateRollback' feature to rollback the failed stack and then redeploy.
Why it's wrong here
ContinueUpdateRollback is designed for the specific case where a stack update (not a creation) fails and you want to return the stack to its previously functioning state. A stack in CREATE_FAILED state has no previous healthy state to roll back to; invoking this API will attempt to rollback the creation, which effectively deletes all resources instead of resuming or completing the creation. Therefore, it is not a mechanism to retry or correct a failed initial deployment.
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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.