CKS Minimize Microservice Vulnerabilities Practice Question
This CKS practice question tests your understanding of minimize microservice vulnerabilities. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which TWO of the following are valid ways to enforce that containers run with a read-only root filesystem?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Using a MutatingWebhookConfiguration that adds `readOnlyRootFilesystem: true` to all containers
Options A and D are correct. Setting `readOnlyRootFilesystem: true` in the container's securityContext enforces a read-only root filesystem. A mutating webhook can also add this setting automatically. Option B is incorrect because `runAsNonRoot` does not affect filesystem writability. Option C is incorrect because `securityContext.fsGroup` is about file ownership. Option E is incorrect because `emptyDir` volumes are writable but do not enforce a read-only root.
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.
✗
Setting `runAsNonRoot: true` in the pod's securityContext
Why it's wrong here
This only prevents running as root, not filesystem writability.
✗
Using an emptyDir volume mounted at /
Why it's wrong here
Mounting a writable volume over root does not enforce read-only; it actually makes root writable.
✗
Setting `fsGroup: 1000` in the pod's securityContext
Why it's wrong here
This sets the group ID for volumes, not read-only root.
✓
Using a MutatingWebhookConfiguration that adds `readOnlyRootFilesystem: true` to all containers
Why this is correct
A mutating webhook can automatically inject the setting.
Related concept
Read the scenario before looking for a memorised answer.
✓
Setting `readOnlyRootFilesystem: true` in the container's securityContext
Why this is correct
This directly sets the filesystem to read-only.
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 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.
Identify which CKS 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.
Minimize Microservice Vulnerabilities — This question tests Minimize Microservice Vulnerabilities — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Using a MutatingWebhookConfiguration that adds `readOnlyRootFilesystem: true` to all containers — Options A and D are correct. Setting `readOnlyRootFilesystem: true` in the container's securityContext enforces a read-only root filesystem. A mutating webhook can also add this setting automatically. Option B is incorrect because `runAsNonRoot` does not affect filesystem writability. Option C is incorrect because `securityContext.fsGroup` is about file ownership. Option E is incorrect because `emptyDir` volumes are writable but do not enforce a read-only root.
What should I do if I get this CKS question wrong?
Identify which CKS 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.
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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