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Question 54 of 1,616

Deployment →mediumMultiple ChoiceObjective-mapped

DVA-C02 Deployment Practice Question

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 company uses AWS CodeDeploy to deploy a web application to an Auto Scaling group. The deployment fails with the error 'The overall deployment failed because too many individual instances failed deployment'. The deployment configuration is set to CodeDeployDefault.OneAtATime. What is the most likely cause of this failure?

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.

Question 1mediummultiple choice

Full question →

A
The instances in the Auto Scaling group are not running a supported operating system.
Why wrong: Unsupported OS would cause a different error during the deployment, not a 'too many instances failed' error.
B
The deployment configuration should be changed to AllAtOnce to avoid this error.
Why wrong: AllAtOnce would deploy to all instances simultaneously, which could also fail if too many instances fail.
C
The IAM role for CodeDeploy does not have sufficient permissions.
Why wrong: A missing IAM role would cause a permission error, not a too many instances failed error.
D
The deployment failed on a single instance, causing the overall deployment to fail because the minimum number of healthy hosts was not maintained.
With OneAtATime, if one instance fails, the deployment fails because the minimum healthy hosts threshold is not met.

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 deployment failed on a single instance, causing the overall deployment to fail because the minimum number of healthy hosts was not maintained.

With CodeDeployDefault.OneAtATime, the deployment updates one instance at a time and requires that a minimum number of healthy hosts be maintained throughout the process. If a single instance fails its deployment, the overall deployment fails because the minimum healthy host threshold is breached—CodeDeploy cannot proceed to the next instance without risking service availability. This error indicates that the failure on one instance caused the entire deployment to abort, not that multiple instances failed independently.

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 instances in the Auto Scaling group are not running a supported operating system.
Why it's wrong here
Unsupported OS would cause a different error during the deployment, not a 'too many instances failed' error.
✗
The deployment configuration should be changed to AllAtOnce to avoid this error.
Why it's wrong here
AllAtOnce would deploy to all instances simultaneously, which could also fail if too many instances fail.
✗
The IAM role for CodeDeploy does not have sufficient permissions.
Why it's wrong here
A missing IAM role would cause a permission error, not a too many instances failed error.
✓
The deployment failed on a single instance, causing the overall deployment to fail because the minimum number of healthy hosts was not maintained.
Why this is correct
With OneAtATime, if one instance fails, the deployment fails because the minimum healthy hosts threshold is not met.
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.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates assume 'too many individual instances failed' means multiple instances failed independently, when in fact with OneAtATime a single instance failure is enough to fail the entire deployment because the minimum healthy hosts requirement is not maintained.

Detailed technical explanation

How to think about this question

CodeDeployDefault.OneAtATime uses a minimum healthy hosts calculation based on the Auto Scaling group's desired capacity; if even one instance fails, the healthy count drops below the threshold (e.g., 1 out of 1 instance fails, leaving 0 healthy), causing the deployment to stop immediately. This behavior is defined in the deployment configuration's 'minimumHealthyHosts' parameter, which for OneAtATime is effectively 0 (or a percentage that allows only one failure). In real-world scenarios, this error often occurs when the application's lifecycle hooks or scripts fail on a single instance due to missing dependencies or configuration drift, and the deployment does not have a fallback or rollback strategy for that single failure.

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.

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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 deployment failed on a single instance, causing the overall deployment to fail because the minimum number of healthy hosts was not maintained. — With CodeDeployDefault.OneAtATime, the deployment updates one instance at a time and requires that a minimum number of healthy hosts be maintained throughout the process. If a single instance fails its deployment, the overall deployment fails because the minimum healthy host threshold is breached—CodeDeploy cannot proceed to the next instance without risking service availability. This error indicates that the failure on one instance caused the entire deployment to abort, not that multiple instances failed independently.

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

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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.

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