The answer is that the buildspec does not include the pre_build step to authenticate with ECR. Even though the IAM role has the AmazonEC2ContainerRegistryPowerUser policy, which grants the necessary permissions to push images, CodeBuild cannot automatically authenticate with the registry. The buildspec must explicitly run the aws ecr get-login-password command and pipe it to docker login during the pre_build phase, otherwise Docker has no credentials to use when pushing, resulting in the 'no basic authentication credentials' error. On the AWS Certified Developer Associate DVA-C02 exam, this question tests your understanding that IAM permissions alone are not enough—the authentication step is a separate, required action in the build process. A common trap is assuming the IAM policy handles everything, but the CLI command is what actually generates the temporary token. Remember the memory tip: "Policy permits, but login performs."
DVA-C02 Troubleshooting and Optimization Practice Question
This DVA-C02 practice question tests your understanding of troubleshooting and optimization. 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 developer is using AWS CodeBuild to build a Docker image and push it to Amazon ECR. The build fails with the error 'no basic authentication credentials'. The build project has an IAM role with the AmazonEC2ContainerRegistryPowerUser policy. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The buildspec does not include the pre_build step to authenticate with ECR.
CodeBuild needs to authenticate with ECR before pushing. The IAM role provides permissions, but the buildspec must include the aws ecr get-login-password command and pipe it to docker login. Option C is correct. Option A is wrong because the policy is sufficient. Option B is wrong because Docker is available. Option D is wrong because network connectivity is typically fine.
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 build project is not configured to use a VPC that can reach ECR.
Why it's wrong here
ECR is accessible from the internet; VPC not required.
✗
The build environment does not have Docker installed.
Why it's wrong here
CodeBuild Docker images include Docker.
✗
The IAM role does not have sufficient permissions to push to ECR.
The buildspec does not include the pre_build step to authenticate with ECR.
Why this is correct
Without authentication, Docker cannot push to ECR.
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
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.
Troubleshooting and Optimization — This question tests Troubleshooting and Optimization — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The buildspec does not include the pre_build step to authenticate with ECR. — CodeBuild needs to authenticate with ECR before pushing. The IAM role provides permissions, but the buildspec must include the aws ecr get-login-password command and pipe it to docker login. Option C is correct. Option A is wrong because the policy is sufficient. Option B is wrong because Docker is available. Option D is wrong because network connectivity is typically fine.
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.
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Question Discussion
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