- A
The ALB health check is misconfigured, causing healthy tasks to be marked as unhealthy and replaced.
Why wrong: Incorrect: Health checks affect routing, not task count.
- B
The service is using the CODE_DEPLOY deployment controller instead of the default ECS rolling update controller.
Correct: With CODE_DEPLOY controller, ECS does not manage the rollout; it stops tasks and waits for external deployment.
- C
The minimumHealthyPercent value of 50% is too low, allowing the service to scale down to 0 tasks.
Why wrong: Incorrect: minimumHealthyPercent=50% should keep at least 2 tasks out of 4.
- D
The ALB deregistration delay is set to 0, causing tasks to be removed immediately.
Why wrong: Incorrect: Deregistration delay affects connection draining, not task count.
DVA-C02 Development with AWS Services Practice Question
This DVA-C02 practice question tests your understanding of development with aws services. 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 developer is deploying a new version of a microservice that runs on AWS Fargate. The service is part of an Amazon ECS cluster and has an associated Application Load Balancer (ALB). The developer wants to perform a rolling update without downtime and ensure that at least 50% of the service's desired count remains available during the deployment. The current desired count is 4. The developer updates the task definition and triggers a new service deployment using the AWS CLI. After the update, the developer notices that the service briefly goes to 0 running tasks during the deployment, causing downtime. The ECS service deployment configuration has: minimumHealthyPercent=50 and maximumPercent=200. What is the most likely cause of this downtime?
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.
Clue:
"least"Why it matters: You want the option with minimum overhead, fewest steps, or lowest impact — not the most feature-rich or comprehensive answer.
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 service is using the CODE_DEPLOY deployment controller instead of the default ECS rolling update controller.
Option B is correct because the deployment controller default is ECS, not CODE_DEPLOY. ECS rolling update with min/max settings should work, but if the deployment controller is set to 'CODE_DEPLOY', the service does not manage the rollout automatically; it expects an external deployment. In this case, the developer triggered a new deployment with the updated task definition but the service might have been configured with CODE_DEPLOY controller, causing it to stop all tasks. Option A is incorrect because 50% minimum healthy percent should keep at least 2 tasks. Option C is incorrect because deregistration delay affects draining, not immediate 0 count. Option D is incorrect because the ALB health check doesn't cause tasks to stop.
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 ALB health check is misconfigured, causing healthy tasks to be marked as unhealthy and replaced.
Why it's wrong here
Incorrect: Health checks affect routing, not task count.
- ✓
The service is using the CODE_DEPLOY deployment controller instead of the default ECS rolling update controller.
Why this is correct
Correct: With CODE_DEPLOY controller, ECS does not manage the rollout; it stops tasks and waits for external deployment.
Clue confirmation
The clue words "most likely", "least" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The minimumHealthyPercent value of 50% is too low, allowing the service to scale down to 0 tasks.
Why it's wrong here
Incorrect: minimumHealthyPercent=50% should keep at least 2 tasks out of 4.
- ✗
The ALB deregistration delay is set to 0, causing tasks to be removed immediately.
Why it's wrong here
Incorrect: Deregistration delay affects connection draining, not task count.
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 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 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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Development with AWS Services — study guide chapter
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Development with AWS Services practice questions
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FAQ
Questions learners often ask
What does this DVA-C02 question test?
Development with AWS Services — This question tests Development with AWS Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The service is using the CODE_DEPLOY deployment controller instead of the default ECS rolling update controller. — Option B is correct because the deployment controller default is ECS, not CODE_DEPLOY. ECS rolling update with min/max settings should work, but if the deployment controller is set to 'CODE_DEPLOY', the service does not manage the rollout automatically; it expects an external deployment. In this case, the developer triggered a new deployment with the updated task definition but the service might have been configured with CODE_DEPLOY controller, causing it to stop all tasks. Option A is incorrect because 50% minimum healthy percent should keep at least 2 tasks. Option C is incorrect because deregistration delay affects draining, not immediate 0 count. Option D is incorrect because the ALB health check doesn't cause tasks to stop.
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", "least". 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
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Last reviewed: Jun 20, 2026
This DVA-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 DVA-C02 exam.
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