Quick Answer
The answer is that the CodeBuild project does not have privileged mode enabled. This is the most likely cause because CodeBuild’s managed environment only grants access to the Docker daemon when the build runs in privileged mode; without it, any Docker command—such as logging into Amazon ECR—will fail with the “Cannot connect to the Docker daemon” error. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of how CodeBuild’s compute types control Docker availability, often appearing as a trap where candidates overlook the need to set `privileged: true` in the buildspec or project configuration. A common memory tip is to think of “privileged” as the key that unlocks the Docker socket—without it, the daemon is simply not running in the container. Remember: no privileged mode, no Docker daemon.
This DOP-C02 practice question tests your understanding of sdlc automation. 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 CodeBuild to compile and test code. The buildspec.yaml includes a pre_build phase that runs 'aws ecr get-login-password --region us-east-1 | docker login --username AWS --password-stdin 123456789012.dkr.ecr.us-east-1.amazonaws.com'. The build fails with 'Error: Cannot connect to the Docker daemon'. 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.
The CodeBuild project does not have privileged mode enabled.
Docker commands require privileged mode in CodeBuild.
The region specified does not match the ECR repository region.
Why wrong: The region matches.
The Docker login command syntax is incorrect.
Why wrong: The syntax is correct for ECR login.
The AWS CLI is not installed in the CodeBuild environment.
Why wrong: AWS CLI is available in CodeBuild environments.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The CodeBuild project does not have privileged mode enabled.
Option D is correct because CodeBuild runs in a managed environment where the Docker daemon is only available if the compute type is set to a privileged mode (e.g., by setting 'privileged: true' in buildspec). Option A is wrong because the command is syntactically correct. Option B is wrong because the ECR login command is correct. Option C is wrong because the region is specified.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
The CodeBuild project does not have privileged mode enabled.
Why this is correct
Docker commands require privileged mode in CodeBuild.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Authentication checks who the user is.
The region specified does not match the ECR repository region.
Why it's wrong here
The region matches.
The Docker login command syntax is incorrect.
Why it's wrong here
The syntax is correct for ECR login.
The AWS CLI is not installed in the CodeBuild environment.
Why it's wrong here
AWS CLI is available in CodeBuild environments.
Common exam traps
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related DOP-C02 questions on access control and AAA configuration.
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FAQ
SDLC Automation — This question tests SDLC Automation — Authentication checks who the user is..
The correct answer is: The CodeBuild project does not have privileged mode enabled. — Option D is correct because CodeBuild runs in a managed environment where the Docker daemon is only available if the compute type is set to a privileged mode (e.g., by setting 'privileged: true' in buildspec). Option A is wrong because the command is syntactically correct. Option B is wrong because the ECR login command is correct. Option C is wrong because the region is specified.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related DOP-C02 questions on access control and AAA configuration.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Authentication checks who the user is.
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Last reviewed: Jun 20, 2026
This DOP-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 DOP-C02 exam.
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