CKAD Practice Question: Application Environment, Configuration and Security
This CKAD practice question tests your understanding of application environment, configuration and security. 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 pod fails to start with a 'CreateContainerConfigError'. Running 'kubectl describe pod my-pod' reveals: 'Error: container has runAsNonRoot and image will run as root'. The pod definition includes 'securityContext.runAsNonRoot: true'. 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 container does not have the CAP_SYS_ADMIN capability
Why wrong: Capabilities are unrelated to the runAsNonRoot check.
B
The container image's default user is root (UID 0), conflicting with runAsNonRoot
runAsNonRoot: true requires the container to run as a non-root user. If the image defaults to root, the pod will fail with this error.
C
The container's filesystem is read-only
Why wrong: readOnlyRootFilesystem does not affect user ID validation.
D
The runAsUser field is missing, so the pod uses a random UID
Why wrong: runAsUser is optional; if omitted, the container runs as the image's default user. The error specifically states the image will run as root.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The container image's default user is root (UID 0), conflicting with runAsNonRoot
The error 'container has runAsNonRoot and image will run as root' occurs because the pod's securityContext sets `runAsNonRoot: true`, but the container image's default user is root (UID 0). Kubernetes checks the image's user at container startup; if the image runs as root and the pod enforces non-root, the container fails to start with a CreateContainerConfigError.
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 container does not have the CAP_SYS_ADMIN capability
Why it's wrong here
Capabilities are unrelated to the runAsNonRoot check.
✓
The container image's default user is root (UID 0), conflicting with runAsNonRoot
Why this is correct
runAsNonRoot: true requires the container to run as a non-root user. If the image defaults to root, the pod will fail with this error.
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 container's filesystem is read-only
Why it's wrong here
readOnlyRootFilesystem does not affect user ID validation.
✗
The runAsUser field is missing, so the pod uses a random UID
Why it's wrong here
runAsUser is optional; if omitted, the container runs as the image's default user. The error specifically states the image will run as root.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume the error is about missing runAsUser or capabilities, but the error message directly points to the image's default user being root, which is a mismatch with the runAsNonRoot constraint.
Detailed technical explanation
How to think about this question
Under the hood, Kubernetes uses the container runtime (e.g., containerd) to inspect the image's USER directive in the Dockerfile. If the image does not specify a non-root user, the default is root (UID 0). The `runAsNonRoot: true` setting triggers a pre-start validation that rejects the container if the image's user is 0. A common real-world scenario is using a base image like `ubuntu:latest` without a `USER` instruction, causing this error when combined with a security policy requiring non-root.
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 practitioner preparing for the CKAD exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CKAD question in full detail.
Application Environment, Configuration and Security — This question tests Application Environment, Configuration and Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The container image's default user is root (UID 0), conflicting with runAsNonRoot — The error 'container has runAsNonRoot and image will run as root' occurs because the pod's securityContext sets `runAsNonRoot: true`, but the container image's default user is root (UID 0). Kubernetes checks the image's user at container startup; if the image runs as root and the pod enforces non-root, the container fails to start with a CreateContainerConfigError.
What should I do if I get this CKAD 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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Question Discussion
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