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 security auditor wants to ensure that no container in the cluster has the CAP_SYS_ADMIN capability. Which of the following is the most effective way to enforce this cluster-wide?
Why wrong: PodSecurityPolicy is deprecated and removed.
B
Modify the kubelet to disallow CAP_SYS_ADMIN
Why wrong: Kubelet does not have a configuration to disallow specific capabilities.
C
Implement a mutating admission webhook that automatically drops CAP_SYS_ADMIN from all pods
An admission webhook can enforce policies cluster-wide automatically.
D
Configure each namespace with 'pod-security.kubernetes.io/enforce: restricted'
Why wrong: Restricted actually allows CAP_SYS_ADMIN? No, restricted drops all capabilities and does not allow adding CAP_SYS_ADMIN. However, labeling each namespace is manual and not cluster-wide by default.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Implement a mutating admission webhook that automatically drops CAP_SYS_ADMIN from all pods
Option C is correct because a mutating admission webhook intercepts Pod creation requests and can automatically modify the pod spec to drop CAP_SYS_ADMIN before the pod is persisted. This approach works cluster-wide, is not deprecated like PodSecurityPolicy, and does not require modifying node-level components or relying on namespace-level enforcement that only warns or rejects but does not automatically drop capabilities.
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.
✗
Add a PodSecurityPolicy that drops CAP_SYS_ADMIN
Why it's wrong here
PodSecurityPolicy is deprecated and removed.
✗
Modify the kubelet to disallow CAP_SYS_ADMIN
Why it's wrong here
Kubelet does not have a configuration to disallow specific capabilities.
✓
Implement a mutating admission webhook that automatically drops CAP_SYS_ADMIN from all pods
Why this is correct
An admission webhook can enforce policies cluster-wide automatically.
Related concept
Read the scenario before looking for a memorised answer.
✗
Configure each namespace with 'pod-security.kubernetes.io/enforce: restricted'
Why it's wrong here
Restricted actually allows CAP_SYS_ADMIN? No, restricted drops all capabilities and does not allow adding CAP_SYS_ADMIN. However, labeling each namespace is manual and not cluster-wide by default.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse Pod Security Standards (PSS) with automatic capability dropping, but the 'restricted' profile only enforces a deny-list on explicit capability requests, not a mutation to drop inherited capabilities.
Detailed technical explanation
How to think about this question
A mutating admission webhook uses an HTTP callback (over TLS) to modify admission requests based on a ValidatingWebhookConfiguration or MutatingWebhookConfiguration resource. Under the hood, the webhook can patch the pod's securityContext.capabilities.drop field to include 'ALL' or 'SYS_ADMIN', ensuring that even if the container image or runtime defaults include CAP_SYS_ADMIN, it is explicitly removed. In real-world scenarios, this is critical because many base images (e.g., from Docker Hub) run with default capabilities that include SYS_ADMIN, and without a mutating webhook, those pods would retain the capability.
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: Implement a mutating admission webhook that automatically drops CAP_SYS_ADMIN from all pods — Option C is correct because a mutating admission webhook intercepts Pod creation requests and can automatically modify the pod spec to drop CAP_SYS_ADMIN before the pod is persisted. This approach works cluster-wide, is not deprecated like PodSecurityPolicy, and does not require modifying node-level components or relying on namespace-level enforcement that only warns or rejects but does not automatically drop capabilities.
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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