This CKS practice question tests your understanding of system hardening. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 is running Kubernetes 1.24. The security team wants to enforce that all pods run with a read-only root filesystem. Which approach is most effective?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable PodSecurity admission controller with restricted profile
Option C is correct because in Kubernetes 1.24, PodSecurityPolicy (PSP) has been removed, and the PodSecurity admission controller with the restricted profile is the built-in replacement that enforces a read-only root filesystem for all pods. The restricted profile sets `securityContext.readOnlyRootFilesystem: true` by default, ensuring compliance without external tools.
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.
✗
Use OPA Gatekeeper to deny pods without readOnlyRootFilesystem
Why it's wrong here
While possible, OPA Gatekeeper is an external tool; the question asks for the most effective built-in approach.
✗
Enable PodSecurityPolicy with readOnlyRootFilesystem: true
Why it's wrong here
PodSecurityPolicy was removed in Kubernetes 1.25, so it's not available in 1.24 (deprecated).
✓
Enable PodSecurity admission controller with restricted profile
Why this is correct
The restricted profile enforces readOnlyRootFilesystem: true as part of the policy.
Related concept
Read the scenario before looking for a memorised answer.
✗
Set --read-only-port=0 in kubelet
Why it's wrong here
This disables the read-only port but does not enforce read-only filesystem for containers.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the removal of PodSecurityPolicy in Kubernetes 1.25 and expects candidates to know that the PodSecurity admission controller with the restricted profile is the direct replacement, not OPA Gatekeeper or deprecated PSP.
Detailed technical explanation
How to think about this question
The PodSecurity admission controller evaluates pods against three predefined profiles (privileged, baseline, restricted) based on namespace labels. The restricted profile enforces `readOnlyRootFilesystem: true` along with other security constraints like `runAsNonRoot: true` and `seccompProfile: RuntimeDefault`. This approach leverages Kubernetes native admission control without external dependencies, making it the most effective and maintainable solution for cluster-wide enforcement.
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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
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: Enable PodSecurity admission controller with restricted profile — Option C is correct because in Kubernetes 1.24, PodSecurityPolicy (PSP) has been removed, and the PodSecurity admission controller with the restricted profile is the built-in replacement that enforces a read-only root filesystem for all pods. The restricted profile sets `securityContext.readOnlyRootFilesystem: true` by default, ensuring compliance without external tools.
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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