CKA Practice Question: Cluster Architecture, Installation & Configuration
This CKA practice question tests your understanding of cluster architecture, installation & configuration. 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 cluster administrator has configured a PodSecurityPolicy (PSP) that requires all pods to run with read-only root filesystem. However, a newly deployed pod is failing to start with the error 'container has runAsNonRoot and image will run as root'. The PSP is designed to prevent running as root. 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 container image is configured to run as root user.
The error message 'container has runAsNonRoot and image will run as root' indicates that the PodSecurityPolicy (PSP) is configured with `runAsNonRoot: true`, but the container image itself is built to run as the root user (UID 0). The PSP enforces that the container must not run as root, but the image's default user is root, causing the admission controller to reject the pod. Option C correctly identifies this mismatch as the most likely cause.
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 PodSecurityPolicy admission controller is not enabled.
Why it's wrong here
If not enabled, the PSP would not be enforced.
✗
The PSP is not set to enforce read-only root filesystem.
Why it's wrong here
The error is about runAsNonRoot, not read-only filesystem.
✓
The container image is configured to run as root user.
Why this is correct
The PSP requires runAsNonRoot, but the image runs as root.
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 PSP is not being applied to the pod's service account.
Why it's wrong here
If it weren't applied, the pod would start without error.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse the 'read-only root filesystem' constraint with the 'runAsNonRoot' constraint, or assume the error is about PSP not being applied, when in fact the error message directly points to the image running as root despite the PSP requiring non-root execution.
Detailed technical explanation
How to think about this question
Under the hood, the PodSecurityPolicy admission controller evaluates the `runAsNonRoot` field by checking the container image's `USER` directive in the Dockerfile. If the image does not specify a non-root user (or explicitly sets USER root), the container's effective UID is 0, which violates `runAsNonRoot: true`. In real-world scenarios, this often occurs when using base images like `ubuntu:latest` or `nginx:latest` that default to root, and the pod spec does not override the security context with `runAsUser: 1000`. The fix is either to use a non-root image or explicitly set `runAsUser` in the pod's security context.
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 CKA 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 CKA question in full detail.
Cluster Architecture, Installation & Configuration — This question tests Cluster Architecture, Installation & Configuration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The container image is configured to run as root user. — The error message 'container has runAsNonRoot and image will run as root' indicates that the PodSecurityPolicy (PSP) is configured with `runAsNonRoot: true`, but the container image itself is built to run as the root user (UID 0). The PSP enforces that the container must not run as root, but the image's default user is root, causing the admission controller to reject the pod. Option C correctly identifies this mismatch as the most likely cause.
What should I do if I get this CKA 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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