This CKA practice question tests your understanding of cluster architecture, installation and configuration. 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 command is used to prevent a node from being scheduled with new pods?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "which command"
Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
kubectl cordon <node>
Correct command.
kubectl taint <node> key=value:NoSchedule
Why wrong: Taints prevent pods without tolerations, but not all pods.
kubectl patch node <node> -p '{"spec":{"unschedulable":true}}'
Why wrong: While this works, cordon is the standard command.
kubectl drain <node>
Why wrong: Drain evicts pods and cordons.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
kubectl cordon <node>
The `kubectl cordon <node>` command marks a node as unschedulable, preventing new pods from being scheduled onto it while leaving existing pods running. This is the standard Kubernetes command for this purpose, directly setting the `spec.unschedulable` field to `true` on the node object.
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.
kubectl cordon <node>
Why this is correct
Correct command.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
kubectl taint <node> key=value:NoSchedule
Why it's wrong here
Taints prevent pods without tolerations, but not all pods.
kubectl patch node <node> -p '{"spec":{"unschedulable":true}}'
Why it's wrong here
While this works, cordon is the standard command.
kubectl drain <node>
Why it's wrong here
Drain evicts pods and cordons.
Common exam traps
The trap here is that candidates confuse `kubectl taint` with `kubectl cordon`, thinking a NoSchedule taint universally blocks all pods, when in fact it only blocks pods without matching tolerations, whereas cordon blocks all new pods unconditionally.
Trap categories for this question
Command / output trap
While this works, cordon is the standard command.
Detailed technical explanation
Under the hood, `kubectl cordon` modifies the node's `.spec.unschedulable` field to `true`, which the kube-scheduler reads during its scheduling cycle to exclude the node from `Predicate` checks (specifically the `CheckNodeUnschedulable` predicate). A real-world scenario is performing node maintenance: you cordon the node first to stop new workloads, then drain it to evict existing pods, ensuring zero-downtime upgrades.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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What to study next
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FAQ
Cluster Architecture, Installation and Configuration — This question tests Cluster Architecture, Installation and Configuration — Read the scenario before looking for a memorised answer..
The correct answer is: kubectl cordon <node> — The `kubectl cordon <node>` command marks a node as unschedulable, preventing new pods from being scheduled onto it while leaving existing pods running. This is the standard Kubernetes command for this purpose, directly setting the `spec.unschedulable` field to `true` on the node object.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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