CKA Practice Question: Cluster Architecture, Installation and Configuration
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 kubectl command is used to mark a node as unschedulable so that no new pods are scheduled onto it?
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 by setting the `node.Spec.Unschedulable` field to `true`. This prevents the Kubernetes scheduler from placing any new pods onto that node, while existing pods continue to run unaffected. This is the correct command for the described task.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
kubectl taint <node>
Why it's wrong here
Taint adds a taint to the node, which repels pods without tolerations, but does not directly make it unschedulable.
✗
kubectl uncordon <node>
Why it's wrong here
Uncordon marks the node as schedulable, the opposite of what is needed.
✗
kubectl drain <node>
Why it's wrong here
Drain evicts pods and also cordons the node, but the question asks specifically for marking unschedulable without evicting.
✓
kubectl cordon <node>
Why this is correct
Cordon marks the node as unschedulable, preventing new pods from being scheduled.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is confusing `cordon` with `drain`—candidates often pick `drain` because they think it makes the node unschedulable, but `drain` additionally evicts all pods, which is not what the question asks for.
Detailed technical explanation
How to think about this question
Under the hood, `kubectl cordon` modifies the node object in etcd via the Kubernetes API, toggling the `spec.unschedulable` field. The kube-scheduler watches for this field change and filters out cordoned nodes during its scheduling cycle. A real-world scenario is performing node maintenance: you cordon the node first to prevent new pods, then drain it to evict existing pods, ensuring zero downtime for workloads.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the CKA 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CKA question in full detail.
Cluster Architecture, Installation and Configuration — This question tests Cluster Architecture, Installation and Configuration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: kubectl cordon <node> — The `kubectl cordon <node>` command marks a node as unschedulable by setting the `node.Spec.Unschedulable` field to `true`. This prevents the Kubernetes scheduler from placing any new pods onto that node, while existing pods continue to run unaffected. This is the correct command for the described task.
What should I do if I get this CKA question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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