This CKS practice question tests your understanding of cluster setup and hardening. 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 admission plugin should be enabled on the kubelet to ensure it only registers nodes and sets labels as allowed by the Node REST API?
PodSecurity
Why wrong: PodSecurity is for enforcing Pod Security Standards, not for restricting kubelet actions.
NodeRestriction
NodeRestriction limits the kubelet's self-modification capabilities, enhancing security.
DenyEscalatingExec
Why wrong: This plugin is deprecated and not relevant to kubelet restrictions.
AlwaysPullImages
Why wrong: AlwaysPullImages ensures images are always pulled, but does not restrict kubelet actions.
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 is the correct choice because it limits the kubelet's ability to modify node and pod labels, ensuring that nodes can only register themselves and set labels that are explicitly allowed by the Node REST API. This plugin enforces a whitelist of labels that the kubelet can set, preventing privilege escalation through label manipulation.
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.
PodSecurity
Why it's wrong here
PodSecurity is for enforcing Pod Security Standards, not for restricting kubelet actions.
NodeRestriction
Why this is correct
NodeRestriction limits the kubelet's self-modification capabilities, enhancing security.
Related concept
Read the scenario before looking for a memorised answer.
DenyEscalatingExec
Why it's wrong here
This plugin is deprecated and not relevant to kubelet restrictions.
AlwaysPullImages
Why it's wrong here
AlwaysPullImages ensures images are always pulled, but does not restrict kubelet actions.
Common exam traps
CNCF often tests the NodeRestriction plugin by pairing it with other admission controllers like PodSecurity or AlwaysPullImages, leading candidates to confuse node-level restrictions with pod-level security policies.
Detailed technical explanation
The NodeRestriction plugin works by intercepting kubelet requests to the Kubernetes API server and verifying that the kubelet is only modifying its own node object (based on the node name in its credential) and only setting labels from a predefined set (e.g., kubernetes.io/hostname, topology.kubernetes.io/zone). Under the hood, it uses the kubelet's TLS certificate identity to enforce that a kubelet cannot label or taint another node, which is critical in multi-tenant clusters to prevent a compromised kubelet from escalating privileges across nodes.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
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 is the correct choice because it limits the kubelet's ability to modify node and pod labels, ensuring that nodes can only register themselves and set labels that are explicitly allowed by the Node REST API. This plugin enforces a whitelist of labels that the kubelet can set, preventing privilege escalation through label manipulation.
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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