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 API server to enforce that kubelet cannot modify nodes other than its own?
NodeSelector
Why wrong: NodeSelector is not an admission plugin.
PodSecurity
Why wrong: PodSecurity is for pod security standards, not node restrictions.
NodeRestriction
Correct. NodeRestriction ensures kubelet can only modify its own node.
AlwaysPullImages
Why wrong: This plugin ensures images are always pulled, unrelated to kubelet node modification.
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 a kubelet can only modify its own Node object and Pods bound to it. This prevents a compromised or misconfigured kubelet from tampering with other nodes, enforcing the principle of least privilege. Without this plugin, a kubelet could potentially update labels, taints, or status on any node, leading to cluster instability or privilege escalation.
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.
NodeSelector
Why it's wrong here
NodeSelector is not an admission plugin.
PodSecurity
Why it's wrong here
PodSecurity is for pod security standards, not node restrictions.
NodeRestriction
Why this is correct
Correct. NodeRestriction ensures kubelet can only modify its own node.
Related concept
Read the scenario before looking for a memorised answer.
AlwaysPullImages
Why it's wrong here
This plugin ensures images are always pulled, unrelated to kubelet node modification.
Common exam traps
CNCF often tests the distinction between admission plugins that control Pod behavior (like PodSecurity or AlwaysPullImages) versus those that control kubelet authorization (NodeRestriction), leading candidates to confuse Pod-level security with node-level access control.
Detailed technical explanation
The NodeRestriction plugin works by intercepting API requests from kubelets and verifying that the node name in the request matches the kubelet's identity (derived from its TLS certificate or a node name annotation). It also restricts the kubelet from modifying Pods not bound to its node and from setting taints or labels that could affect scheduling decisions for other nodes. In a real-world scenario, if a kubelet is compromised, NodeRestriction limits the blast radius to only that node, preventing lateral movement to other nodes via the API server.
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 a kubelet can only modify its own Node object and Pods bound to it. This prevents a compromised or misconfigured kubelet from tampering with other nodes, enforcing the principle of least privilege. Without this plugin, a kubelet could potentially update labels, taints, or status on any node, leading to cluster instability or privilege escalation.
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 30, 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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