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.
You want to ensure that kubelets only serve pods that have been scheduled by the API server. Which admission plugin should be enabled?
ServiceAccount
Why wrong: Manages service accounts, not pod scheduling.
AlwaysPullImages
Why wrong: This ensures images are always pulled, unrelated to pod binding.
PodNodeSelector
Why wrong: This plugin enforces node selector constraints, not kubelet behavior.
NodeRestriction
This plugin restricts kubelet self-modification and ensures pods are bound to the node.
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 limits the Node and Pod objects a kubelet can modify. When enabled, each kubelet can only create/modify pods bound to its own node, and only pods that have been scheduled by the API server (i.e., have a non-empty `spec.nodeName` set by the scheduler). This prevents a compromised kubelet from creating arbitrary pods or modifying pods on other nodes, enforcing that only the API server schedules pods.
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.
ServiceAccount
Why it's wrong here
Manages service accounts, not pod scheduling.
AlwaysPullImages
Why it's wrong here
This ensures images are always pulled, unrelated to pod binding.
PodNodeSelector
Why it's wrong here
This plugin enforces node selector constraints, not kubelet behavior.
NodeRestriction
Why this is correct
This plugin restricts kubelet self-modification and ensures pods are bound to the node.
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 placement (like PodNodeSelector) with the plugin that restricts kubelet actions (NodeRestriction), leading them to select PodNodeSelector because it sounds related to node selection, but it does not enforce that pods are only created by the API server.
Detailed technical explanation
The NodeRestriction plugin works by intercepting kubelet requests to the API server via the `Node` and `Pod` resource endpoints. It validates that the kubelet's `spec.nodeName` matches the node name in its TLS certificate (or the `--node-name` flag) and only allows pod mutations where `spec.nodeName` is already set to that node. This is critical in multi-tenant clusters where a compromised kubelet could otherwise impersonate another node or create unscheduled pods, bypassing the scheduler's resource allocation and security policies.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
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 limits the Node and Pod objects a kubelet can modify. When enabled, each kubelet can only create/modify pods bound to its own node, and only pods that have been scheduled by the API server (i.e., have a non-empty `spec.nodeName` set by the scheduler). This prevents a compromised kubelet from creating arbitrary pods or modifying pods on other nodes, enforcing that only the API server schedules pods.
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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