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.
An administrator runs 'kubectl describe nodes' and notices that the node status shows 'Ready,SchedulingDisabled'. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The node was cordoned using 'kubectl cordon <node>'
The 'Ready,SchedulingDisabled' status indicates that the node is marked as unschedulable for new pods while remaining fully operational. This is exactly what happens when an administrator runs 'kubectl cordon <node>', which sets the node's 'spec.unschedulable' field to true. The kubelet continues to run and report readiness, but the scheduler will skip the node when placing new pods.
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.
✗
The kubelet is not running
Why it's wrong here
If the kubelet is not running, the node status would be NotReady.
✓
The node was cordoned using 'kubectl cordon <node>'
Why this is correct
Cordoning a node marks it as unschedulable, resulting in SchedulingDisabled.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The node has insufficient resources
Why it's wrong here
Insufficient resources would show conditions like MemoryPressure, not SchedulingDisabled.
✗
The node is tainted with NoSchedule
Why it's wrong here
Taints prevent pod scheduling but do not change the node status to SchedulingDisabled.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the distinction between taints (which affect scheduling based on tolerations) and cordoning (which makes the node completely unschedulable), leading candidates to confuse taint-based scheduling restrictions with the explicit unschedulable flag.
Trap categories for this question
Command / output trap
Insufficient resources would show conditions like MemoryPressure, not SchedulingDisabled.
Detailed technical explanation
How to think about this question
Under the hood, 'kubectl cordon' modifies the node object by setting 'spec.unschedulable: true', which the kubelet reflects in its status as 'Ready,SchedulingDisabled'. The scheduler's predicate check explicitly filters out nodes with this field set to true, regardless of taints or resource availability. This is a common maintenance operation used before draining a node for upgrades or decommissioning.
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 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CKS question in full detail.
Cluster Setup and Hardening — This question tests Cluster Setup and Hardening — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The node was cordoned using 'kubectl cordon <node>' — The 'Ready,SchedulingDisabled' status indicates that the node is marked as unschedulable for new pods while remaining fully operational. This is exactly what happens when an administrator runs 'kubectl cordon <node>', which sets the node's 'spec.unschedulable' field to true. The kubelet continues to run and report readiness, but the scheduler will skip the node when placing new pods.
What should I do if I get this CKS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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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