← DVA-C02·Amazon Web Services

Question 1,052 of 1,616

Deployment →hardMultiple ChoiceObjective-mapped

CodePipeline Manual Approval — Mutable Image Tag Error

This DVA-C02 practice question tests your understanding of deployment. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 CodeBuild to compile and package code, and AWS CodePipeline to orchestrate deployments to Amazon ECS. The pipeline includes a manual approval step. During a recent deployment, the build succeeded but the pipeline failed at the deploy stage with the error 'CannotPullContainerError: manifest for image:tag not found'. The ECS task definition references the image:tag. 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.

A
The CodeBuild project does not have permissions to push to Amazon ECR.
Why wrong: Incorrect because the build succeeded.
B
The ECS cluster does not have internet access to pull the image from ECR.
Why wrong: Incorrect because the error is about manifest, not connectivity.
C
The image tag used is 'latest', and a subsequent build pushed a new 'latest' image, overwriting the original before the manual approval was granted.
Correct because manual approval delays deployment, and 'latest' tag is mutable.
D
The task definition references an incorrect image name.
Why wrong: Incorrect because it worked before.

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 image tag used is 'latest', and a subsequent build pushed a new 'latest' image, overwriting the original before the manual approval was granted.

Option C is correct because when a manual approval step is used in CodePipeline, the image tag referenced in the ECS task definition must remain immutable until the approval is granted. If the tag is 'latest', each subsequent build overwrites the same tag in Amazon ECR. By the time the manual approval is given, the original image:tag no longer exists in the registry, causing the 'CannotPullContainerError: manifest for image:tag not found' error during the deploy stage.

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 CodeBuild project does not have permissions to push to Amazon ECR.
Why it's wrong here
Incorrect because the build succeeded.
✗
The ECS cluster does not have internet access to pull the image from ECR.
Why it's wrong here
Incorrect because the error is about manifest, not connectivity.
✓
The image tag used is 'latest', and a subsequent build pushed a new 'latest' image, overwriting the original before the manual approval was granted.
Why this is correct
Correct because manual approval delays deployment, and 'latest' tag is mutable.
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 task definition references an incorrect image name.
Why it's wrong here
Incorrect because it worked before.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often assume the error is due to network connectivity (Option B) or incorrect image name (Option D), but the specific 'manifest not found' error points to a missing tag, which is a classic consequence of using mutable tags like 'latest' in a pipeline with manual approval.

Detailed technical explanation

How to think about this question

Under the hood, Amazon ECR uses a manifest-based storage system where each image tag is a pointer to a specific manifest digest. When a new build pushes the same tag (e.g., 'latest'), the previous manifest is orphaned and the tag points to the new digest. The ECS agent pulls the image by tag at deploy time; if the tag has been overwritten, the original digest is no longer referenced, causing the pull to fail. This is a common pitfall in CI/CD pipelines with manual approvals, where immutable tags (e.g., Git commit hash or build ID) should be used to ensure each deployment references a fixed artifact.

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 image tag used is 'latest', and a subsequent build pushed a new 'latest' image, overwriting the original before the manual approval was granted. — Option C is correct because when a manual approval step is used in CodePipeline, the image tag referenced in the ECS task definition must remain immutable until the approval is granted. If the tag is 'latest', each subsequent build overwrites the same tag in Amazon ECR. By the time the manual approval is given, the original image:tag no longer exists in the registry, causing the 'CannotPullContainerError: manifest for image:tag not found' error during the deploy stage.

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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