Quick Answer
The answer is the ECS deployment circuit breaker. This feature automatically detects when a new application version in an ECS service fails health checks during a rolling update, and it triggers a rollback to the previous version that is still running. In a deployment with a 200% percent start, the circuit breaker monitors the health of the new tasks; if they fail, it stops the deployment and reverts to the old task set, ensuring minimal disruption. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this concept tests your understanding of automated deployment safety mechanisms versus manual or external solutions. A common trap is confusing the circuit breaker with ECS service auto recovery, which handles infrastructure failures, not deployment failures. Remember the mnemonic “Circuit Breaker Cuts Bad Code” to recall that it is the native ECS feature for automatic rollback on health check failures.
This DOP-C02 practice question tests your understanding of incident and event response. 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.
During a deployment, a new application version on an ECS service starts failing health checks. The previous version is still running. The deployment is a rolling update with a 200% percent start. Which ECS feature should the engineer use to automatically revert to the previous version?
ECS deployment circuit breaker
Circuit breaker automatically rolls back on deployment failure.
ECS service auto recovery
Why wrong: Auto recovery is for instance failure, not deployment failure.
ECS managed scaling
Why wrong: Managed scaling adjusts based on load, not deployment health.
CloudWatch alarm actions
Why wrong: CloudWatch alarms can trigger rollback but are not built into ECS.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
ECS deployment circuit breaker
Option D is correct because a circuit breaker automatically detects deployment failures and rolls back. Option A is wrong because ECS service auto recovery is for underlying infrastructure. Option B is wrong because managed scaling adjusts desired count, not rollback. Option C is wrong because CloudWatch alarms can trigger rollback but are not automatic within ECS itself.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
ECS deployment circuit breaker
Why this is correct
Circuit breaker automatically rolls back on deployment failure.
Related concept
Read the scenario before looking for a memorised answer.
ECS service auto recovery
Why it's wrong here
Auto recovery is for instance failure, not deployment failure.
ECS managed scaling
Why it's wrong here
Managed scaling adjusts based on load, not deployment health.
CloudWatch alarm actions
Why it's wrong here
CloudWatch alarms can trigger rollback but are not built into ECS.
Common exam traps
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
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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
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.
Incident and Event Response — study guide chapter
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FAQ
Incident and Event Response — This question tests Incident and Event Response — Read the scenario before looking for a memorised answer..
The correct answer is: ECS deployment circuit breaker — Option D is correct because a circuit breaker automatically detects deployment failures and rolls back. Option A is wrong because ECS service auto recovery is for underlying infrastructure. Option B is wrong because managed scaling adjusts desired count, not rollback. Option C is wrong because CloudWatch alarms can trigger rollback but are not automatic within ECS itself.
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.
Read the scenario before looking for a memorised answer.
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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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