The answer is that the existing instances are terminated only after the new Auto Scaling group is created and fully operational. This behavior occurs because CloudFormation treats the Auto Scaling group as a resource that must be replaced, not simply updated; when a property like the LaunchTemplate or LaunchConfigurationName changes, the service creates the replacement group first to maintain capacity and minimize downtime. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this concept tests your understanding of CloudFormation’s resource replacement policy and its impact on high-availability architectures—a common trap is assuming instances are terminated immediately or that an in-place update occurs. Remember that CloudFormation prioritizes availability over cost during replacements, so it builds the new group before destroying the old one. A useful memory tip: think “build first, burn later” to recall that the new Auto Scaling group comes alive before the old instances are retired.
DOP-C02 Configuration Management and IaC Practice Question
This DOP-C02 practice question tests your understanding of configuration management and iac. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 DevOps engineer is managing the lifecycle of a CloudFormation stack. The engineer needs to update a stack that contains an Auto Scaling group. The update requires a replacement of the Auto Scaling group. What will happen to the existing instances during the update?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The existing instances will be terminated after the new Auto Scaling group is created
When a CloudFormation stack update requires replacement of an Auto Scaling group (e.g., due to a change in the `LaunchConfigurationName` or `LaunchTemplate` property), CloudFormation creates the new Auto Scaling group first, then terminates the old instances after the new group is fully operational. This ensures minimal downtime because the new group begins serving traffic before the old one is torn down.
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.
✓
The existing instances will be terminated after the new Auto Scaling group is created
Why this is correct
CloudFormation creates the new group first, then deletes the old one, terminating its instances.
Related concept
Read the scenario before looking for a memorised answer.
✗
The stack update will fail because Auto Scaling groups cannot be replaced
Why it's wrong here
Auto Scaling groups can be replaced during stack updates.
✗
The existing instances will remain running and be associated with the new Auto Scaling group
Why it's wrong here
A replacement creates a new group; old instances are not reused.
✗
The instances will be updated in-place by terminating and recreating each instance one by one
Why it's wrong here
CloudFormation replaces the entire group, not individual instances.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume CloudFormation performs in-place updates (Option D) or that replacement always fails (Option B), but the service explicitly supports create-before-destroy replacement for Auto Scaling groups.
Detailed technical explanation
How to think about this question
Under the hood, CloudFormation uses a resource-level `Replacement` policy that defaults to `CreateThenDelete` for Auto Scaling groups. This means the new group is provisioned with its own instances, and the old group is deleted only after the new group passes its creation and health checks. In real-world scenarios, this behavior prevents downtime during rolling updates, but you must ensure the new group can handle traffic before the old one is removed, often by using an Elastic Load Balancer target group swap.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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.
Configuration Management and IaC — This question tests Configuration Management and IaC — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The existing instances will be terminated after the new Auto Scaling group is created — When a CloudFormation stack update requires replacement of an Auto Scaling group (e.g., due to a change in the `LaunchConfigurationName` or `LaunchTemplate` property), CloudFormation creates the new Auto Scaling group first, then terminates the old instances after the new group is fully operational. This ensures minimal downtime because the new group begins serving traffic before the old one is torn down.
What should I do if I get this DOP-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.