- A
The ECS service deployment controller is set to 'ECS' instead of 'CODE_DEPLOY'.
With ECS deployment controller, blue/green deployments do not support automatic rollback; must use CODE_DEPLOY controller to enable CodeDeploy and automatic rollback.
- B
The CodeDeploy application and deployment group are not configured for automatic rollback.
Why wrong: If deployment controller is CODE_DEPLOY, CodeDeploy handles rollback; but the question says deployment does not automatically roll back, suggesting CodeDeploy is not being used.
- C
The health check grace period is set too high.
Why wrong: Grace period delays health checks, but once they start, failure would trigger rollback if configured; not the reason for no rollback.
- D
The ECS service is configured with a 'minimum healthy percent' of 100 percent.
Why wrong: Minimum healthy percent affects how many tasks are replaced, but does not prevent rollback on health check failure.
ECS Blue/Green Deployment Controller Requirement
This DVA-C02 practice question tests your understanding of deployment. 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.
A DevOps engineer is implementing a blue/green deployment for a microservice running on Amazon ECS with Fargate. The service is fronted by an Application Load Balancer. During deployment, the new task set fails health checks, but the deployment does not automatically roll back. What is the MOST likely reason?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
The ECS service deployment controller is set to 'ECS' instead of 'CODE_DEPLOY'.
Option A is correct. For blue/green deployments on ECS, you must specify a deployment controller type of 'CODE_DEPLOY' to use CodeDeploy and enable automatic rollback. If the controller is 'ECS' (the default), the deployment is managed by ECS and does not support automatic rollback on health check failures in blue/green mode. Option B is wrong because ECS does roll back if health checks fail when using ECS deployment controller with rolling update, but not for blue/green. Option C is wrong because CodeDeploy is not used if deployment controller is not CODE_DEPLOY. Option D is wrong because health check grace period delays health checks but does not prevent rollback if checks fail after grace period.
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 ECS service deployment controller is set to 'ECS' instead of 'CODE_DEPLOY'.
Why this is correct
With ECS deployment controller, blue/green deployments do not support automatic rollback; must use CODE_DEPLOY controller to enable CodeDeploy and automatic rollback.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The CodeDeploy application and deployment group are not configured for automatic rollback.
Why it's wrong here
If deployment controller is CODE_DEPLOY, CodeDeploy handles rollback; but the question says deployment does not automatically roll back, suggesting CodeDeploy is not being used.
- ✗
The health check grace period is set too high.
Why it's wrong here
Grace period delays health checks, but once they start, failure would trigger rollback if configured; not the reason for no rollback.
- ✗
The ECS service is configured with a 'minimum healthy percent' of 100 percent.
Why it's wrong here
Minimum healthy percent affects how many tasks are replaced, but does not prevent rollback on health check failure.
Common exam traps
Common exam trap: answer the scenario, not the keyword
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
How to think about this question
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.
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.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- 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 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
Got this wrong? Here's your next step.
Identify which DVA-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.
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FAQ
Questions learners often ask
What does this DVA-C02 question test?
Deployment — This question tests Deployment — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The ECS service deployment controller is set to 'ECS' instead of 'CODE_DEPLOY'. — Option A is correct. For blue/green deployments on ECS, you must specify a deployment controller type of 'CODE_DEPLOY' to use CodeDeploy and enable automatic rollback. If the controller is 'ECS' (the default), the deployment is managed by ECS and does not support automatic rollback on health check failures in blue/green mode. Option B is wrong because ECS does roll back if health checks fail when using ECS deployment controller with rolling update, but not for blue/green. Option C is wrong because CodeDeploy is not used if deployment controller is not CODE_DEPLOY. Option D is wrong because health check grace period delays health checks but does not prevent rollback if checks fail after grace period.
What should I do if I get this DVA-C02 question wrong?
Identify which DVA-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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 →
Same concept, more angles
3 more ways this is tested on DVA-C02
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A developer is using AWS CodeDeploy with a blue/green deployment strategy to update an application running on Amazon ECS with the Fargate launch type. After the new (green) task set is created and traffic is shifted to it, users immediately report errors when trying to write data. The developer discovers that the green task set is connecting to a different database than the blue task set. The database endpoints are configured in the ECS task definition. What is the simplest way to prevent this issue in future deployments?
hard- ✓ A.Modify the blue/green deployment configuration to use the same database endpoint for both task sets by updating the environment variables in the task definition before deployment.
- B.Create two separate Amazon RDS databases and use an Amazon Route 53 weighted routing policy to distribute traffic.
- C.Use an Application Load Balancer (ALB) with stickiness to route each user to the correct task set.
- D.Use AWS CloudFormation to create a new database stack for each deployment and update the task definition dynamically.
Why A: Option A is correct because the issue stems from the green task set using a different database endpoint than the blue task set, which is configured via environment variables in the ECS task definition. By updating the task definition to use the same database endpoint before deployment, both task sets will connect to the same database, ensuring consistency during the traffic shift. This is the simplest fix as it requires no additional infrastructure or complex routing changes.
Variation 2. A CodeDeploy blue/green ECS deployment uses an ALB. Which two resources are required?
hard- ✓ A.Two target groups for original and replacement task sets
- B.A single target group shared by both task sets only
- C.An S3 static website endpoint
- ✓ D.Listener configuration that allows traffic shifting/testing
Why A: Option A is correct because a blue/green deployment in CodeDeploy for ECS requires two distinct target groups: one for the original (blue) task set and one for the replacement (green) task set. The ALB routes traffic to the appropriate target group based on the listener rules, allowing CodeDeploy to shift traffic gradually from the blue to the green task set during deployment.
Variation 3. Which THREE components are required to perform a blue/green deployment of an application running on Amazon ECS using AWS CodeDeploy? (Select THREE.)
hard- A.An Amazon ECS cluster
- ✓ B.An Application Load Balancer
- ✓ C.An AWS CodeDeploy deployment group
- ✓ D.An AWS CodeDeploy application
- E.A target tracking scaling policy
Why B: An Application Load Balancer (ALB) is required for blue/green deployments on Amazon ECS with AWS CodeDeploy because it routes traffic between the 'blue' (current) and 'green' (new) task sets. CodeDeploy uses the ALB's target groups to shift traffic incrementally during the deployment, enabling zero-downtime updates. Without an ALB, there is no mechanism to direct production traffic to the new task set while keeping the old one available for rollback.
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Last reviewed: Jun 20, 2026
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