← DVA-C02·Amazon Web Services

Question 972 of 1,616

Deployment →hardMultiple ChoiceObjective-mapped

CodeDeploy Health Constraints — Minimum Healthy Instances

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. A key principle to apply: codeDeployDefault.AllAtOnce. 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 company is using AWS CodeDeploy with an in-place deployment to an Auto Scaling group. The deployment fails with the error 'Deployment failed because the deployment group does not have enough instances to deploy to'. The Auto Scaling group has a minimum size of 2, maximum size of 5, and desired capacity of 2. The deployment configuration is CodeDeployDefault.AllAtOnce. What is the most likely cause?

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: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.

A
The Auto Scaling group needs to have at least 3 instances to use AllAtOnce.
Why wrong: Incorrect. CodeDeployDefault.AllAtOnce has a minimum healthy hosts value of 0, so it does not require a specific number of instances to start the deployment.
B
The deployment configuration is not compatible with Auto Scaling groups.
Why wrong: Incorrect. CodeDeployDefault.AllAtOnce is compatible with Auto Scaling groups. This error is not due to incompatibility.
C
The instances in the Auto Scaling group are not passing health checks.
Correct. If instances fail health checks, they are not considered healthy, leading to zero healthy instances in the deployment group, which causes this error.
D
The deployment group has only 2 instances, and the deployment failed on one instance, causing the minimum healthy hosts threshold to be violated.
Why wrong: Incorrect. A failure on one instance during deployment does not violate the minimum healthy hosts threshold because AllAtOnce allows all instances to be updated simultaneously with no minimum healthy hosts required.

Full breakdown with real-world context →

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 instances in the Auto Scaling group are not passing health checks.

The error 'Deployment failed because the deployment group does not have enough instances to deploy to' occurs when there are zero healthy instances in the deployment group at the start of deployment. With CodeDeployDefault.AllAtOnce, the minimum number of healthy hosts is 0, so a single instance failure during deployment would not trigger this error. The most likely cause is that the instances in the Auto Scaling group are not passing health checks, resulting in no healthy instances available for deployment. Option C is correct.

Key principle: CodeDeployDefault.AllAtOnce

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 Auto Scaling group needs to have at least 3 instances to use AllAtOnce.
Why it's wrong here
Incorrect. CodeDeployDefault.AllAtOnce has a minimum healthy hosts value of 0, so it does not require a specific number of instances to start the deployment.
✗
The deployment configuration is not compatible with Auto Scaling groups.
Why it's wrong here
Incorrect. CodeDeployDefault.AllAtOnce is compatible with Auto Scaling groups. This error is not due to incompatibility.
✓
The instances in the Auto Scaling group are not passing health checks.
Why this is correct
Correct. If instances fail health checks, they are not considered healthy, leading to zero healthy instances in the deployment group, which causes this error.
Clue confirmation
The clue words "most likely", "minimum / minimize" in the question point toward this answer.
Related concept
CodeDeployDefault.AllAtOnce
✗
The deployment group has only 2 instances, and the deployment failed on one instance, causing the minimum healthy hosts threshold to be violated.
Why it's wrong here
Incorrect. A failure on one instance during deployment does not violate the minimum healthy hosts threshold because AllAtOnce allows all instances to be updated simultaneously with no minimum healthy hosts required.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Candidates often misinterpret this error as a sizing or threshold issue, but it actually indicates that no healthy instances exist at deployment start, typically due to health check failures.

Detailed technical explanation

How to think about this question

CodeDeployDefault.AllAtOnce sets the minimum healthy hosts to 0, meaning the deployment will proceed even if all instances are updated simultaneously, but if any instance fails the deployment, the overall deployment fails because the deployment group must have at least one healthy instance to complete the revision. Under the hood, CodeDeploy calculates the number of 'available instances' based on the deployment group's current healthy instance count, and if the deployment fails on an instance, that instance is marked as failed, reducing the available count below the threshold. In real-world scenarios, this error often occurs when using a small Auto Scaling group (e.g., 2 instances) with AllAtOnce, as a single instance failure can cause the entire deployment to abort.

KKey Concepts to Remember

CodeDeployDefault.AllAtOnce
Minimum healthy hosts
Health checks

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

CodeDeployDefault.AllAtOnce

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. CodeDeployDefault.AllAtOnce 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.

Review codeDeployDefault.AllAtOnce, then practise related DVA-C02 questions on the same topic to reinforce the concept.

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FAQ

Questions learners often ask

What does this DVA-C02 question test?

Deployment — This question tests Deployment — CodeDeployDefault.AllAtOnce.

What is the correct answer to this question?

The correct answer is: The instances in the Auto Scaling group are not passing health checks. — The error 'Deployment failed because the deployment group does not have enough instances to deploy to' occurs when there are zero healthy instances in the deployment group at the start of deployment. With CodeDeployDefault.AllAtOnce, the minimum number of healthy hosts is 0, so a single instance failure during deployment would not trigger this error. The most likely cause is that the instances in the Auto Scaling group are not passing health checks, resulting in no healthy instances available for deployment. Option C is correct.

What should I do if I get this DVA-C02 question wrong?

Review codeDeployDefault.AllAtOnce, then practise related DVA-C02 questions on the same topic to reinforce the concept.

Are there clue words in this question I should notice?

Yes — watch for: "most likely", "minimum / minimize". 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?

CodeDeployDefault.AllAtOnce

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Same concept, more angles

1 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 performed a CodeDeploy deployment to an Auto Scaling group. The deployment status is Failed with code HEALTH_CONSTRAINTS. Based on the exhibit, what is the most likely cause?

hard

A.The CodeDeploy agent on the instances is not running
✓ B.The minimum number of healthy instances required for the deployment was not met
C.The application revision contains invalid scripts
D.The IAM role for CodeDeploy does not have sufficient permissions

Why B: The error 'HEALTH_CONSTRAINTS' means that too many instances failed health checks. The deployment overview shows 2 failed instances and 3 succeeded. The minimum healthy instances setting likely required more than 3 healthy instances. Option B is correct. Option A (incorrect application revision) would cause a different error. Option C (CodeDeploy agent) would show agent issues. Option D (permissions) would cause access denied errors.

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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.