KCNA Kubernetes Fundamentals Practice Question
A pod is stuck in the Pending state. The administrator runs 'kubectl describe pod' and sees the event '0/3 nodes are available: 3 Insufficient cpu.' What is the most likely cause?
⚠ Common exam trap
Candidates often confuse CPU limits with requests; only requests affect scheduling, while limits affect runtime throttling.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The pod's CPU request is higher than the available CPU on any node.
The event 'Insufficient cpu' indicates that the scheduler cannot find a node with enough allocatable CPU to meet the pod's CPU request. This is a resource constraint issue, not related to limits, cordoning, or node selectors. The pod will remain Pending until sufficient CPU is available or the request is reduced.
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 nodes are cordoned and cannot accept new pods.
Why it's wrong here
If nodes were cordoned, the event would indicate that nodes are unschedulable, often with a message like 'node(s) were unschedulable'. The message 'Insufficient cpu' points specifically to resource constraints, not taints or cordoning. Cordoned nodes would produce a different scheduling failure reason.
- ✗
The pod's CPU limit is set too low, causing it to be rejected.
Why it's wrong here
CPU limits do not affect scheduling; only requests are considered. A low CPU limit would not prevent the pod from being scheduled, though it might cause throttling at runtime. The event specifically mentions insufficient CPU, which refers to requests. Limits are enforced by the kubelet after scheduling.
- ✓
The pod's CPU request is higher than the available CPU on any node.
Why this is correct
The scheduler reports 'Insufficient cpu' when no node has enough allocatable CPU to satisfy the pod's CPU request. This means the sum of CPU requests of existing pods plus the new pod's request exceeds the node's capacity. The pod remains Pending until resources are freed or the request is lowered. This is the direct cause of the event.
- ✗
The pod has a nodeSelector that does not match any node labels.
Why it's wrong here
A nodeSelector mismatch would result in an event like '0/3 nodes are available: 3 node(s) didn't match node selector.' The message 'Insufficient cpu' is unrelated to node selectors. It indicates that even if nodes matched, they lack sufficient CPU resources to run the pod.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CNCF exam blueprint
This KCNA 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 KCNA exam.