This CKS practice question tests your understanding of cluster setup and 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.
Which admission plugin should be enabled on the kube-apiserver to enforce that kubelets cannot modify nodes they are not assigned to?
AlwaysPullImages
Why wrong: This enforces image pull policy, not node access control.
NodeSelector
Why wrong: This is not an admission plugin; node selector is a pod field.
PodSecurity
Why wrong: PodSecurity enforces pod security standards, not kubelet node restrictions.
NodeRestriction
NodeRestriction ensures kubelets can only modify their own node objects.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
NodeRestriction
The NodeRestriction admission plugin ensures that kubelets can only modify their own Node API objects and pods bound to them. When enabled, it prevents a kubelet from modifying nodes it is not assigned to, enforcing the principle of least privilege and limiting the blast radius of a compromised kubelet.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
AlwaysPullImages
Why it's wrong here
This enforces image pull policy, not node access control.
NodeSelector
Why it's wrong here
This is not an admission plugin; node selector is a pod field.
PodSecurity
Why it's wrong here
PodSecurity enforces pod security standards, not kubelet node restrictions.
NodeRestriction
Why this is correct
NodeRestriction ensures kubelets can only modify their own node objects.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates confuse admission plugins that control pod behavior (like PodSecurity or AlwaysPullImages) with those that restrict kubelet actions, or they mistakenly think NodeSelector is a security control rather than a scheduling feature.
Detailed technical explanation
The NodeRestriction plugin works by intercepting requests from kubelets (identified via their TLS client certificate) and verifying that the node name in the request matches the kubelet's identity. It also restricts kubelets from modifying labels on their own node unless those labels are in the `kubernetes.io/` or `k8s.io/` prefix and are specifically allowed. This prevents a compromised kubelet from impersonating another node or escalating privileges by altering node metadata.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
What to study next
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FAQ
Cluster Setup and Hardening — This question tests Cluster Setup and Hardening — Read the scenario before looking for a memorised answer..
The correct answer is: NodeRestriction — The NodeRestriction admission plugin ensures that kubelets can only modify their own Node API objects and pods bound to them. When enabled, it prevents a kubelet from modifying nodes it is not assigned to, enforcing the principle of least privilege and limiting the blast radius of a compromised kubelet.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This CKS practice question is part of Courseiva's free CNCF certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CKS exam.
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