This CKS practice question tests your understanding of system hardening. 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.
Exhibit
Refer to the exhibit.
```
apiVersion: v1
kind: Pod
metadata:
name: nginx
spec:
containers:
- name: nginx
image: nginx:1.21
securityContext:
runAsNonRoot: true
runAsUser: 1000
capabilities:
add: ["NET_ADMIN"]
```
Refer to the exhibit. The pod fails to start with the error 'container has runAsNonRoot but image will run as root'. Which change would fix the issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Set runAsNonRoot: false
The error 'container has runAsNonRoot but image will run as root' occurs because the Pod's security context sets `runAsNonRoot: true`, but the container image is configured to run as root (UID 0). Setting `runAsNonRoot: false` removes the enforcement, allowing the container to run as root as the image expects. This directly resolves the conflict between the security context constraint and the image's default user.
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.
✓
Set runAsNonRoot: false
Why this is correct
Removes the non-root requirement, allowing the image to run as root.
Related concept
Read the scenario before looking for a memorised answer.
✗
Change runAsUser to 0
Why it's wrong here
runAsUser=0 would run as root, but runAsNonRoot: true still conflicts.
✗
Use a different image that runs as non-root
Why it's wrong here
That would work but is not the only fix; the question asks for a change to the given manifest.
✗
Add NET_ADMIN capability
Why it's wrong here
The error is about runAsNonRoot, not capabilities.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the misconception that you must change the image or add capabilities to fix a `runAsNonRoot` violation, when in fact the simplest fix is to adjust the security context setting to match the image's behavior.
Detailed technical explanation
How to think about this question
Under the hood, `runAsNonRoot` is enforced by the kubelet's security context validation, which checks the container's effective UID at runtime. If the image's default user is root (UID 0) and `runAsNonRoot: true` is set, the Pod will be rejected before starting. In real-world scenarios, this often occurs when using legacy images that require root, and the correct fix is either to set `runAsNonRoot: false` or to override the user with `runAsUser: 1000` (or another non-zero UID) while keeping `runAsNonRoot: true`.
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 CKS 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 CKS question in full detail.
System Hardening — This question tests System Hardening — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Set runAsNonRoot: false — The error 'container has runAsNonRoot but image will run as root' occurs because the Pod's security context sets `runAsNonRoot: true`, but the container image is configured to run as root (UID 0). Setting `runAsNonRoot: false` removes the enforcement, allowing the container to run as root as the image expects. This directly resolves the conflict between the security context constraint and the image's default user.
What should I do if I get this CKS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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