KCNA Container Orchestration Practice Question
A Kubernetes cluster has a pod that is stuck in the 'Pending' state. The operations team runs 'kubectl describe pod' and sees the event: '0/3 nodes are available: 3 Insufficient cpu.' What is the most likely cause of this issue?
⚠ Common exam trap
Watch out — candidates often confuse CPU limits with requests; only requests affect scheduling, and the error message explicitly points to insufficient CPU resources.
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 exceeds the allocatable 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 happens when the sum of CPU requests from existing pods on each node plus the new pod's request exceeds the node's capacity. The pod remains Pending until resources are freed or the request is lowered. Other factors like taints or node selectors would produce different event messages.
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 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 event here specifically mentions insufficient CPU, so the issue is resource-related, not label-based. The scheduler filters nodes by both labels and resources, but the error message pinpoints CPU shortage.
- ✗
The nodes have CPU resources but are tainted, preventing scheduling.
Why it's wrong here
If nodes were tainted, the scheduler would report that no nodes are available due to taints, not insufficient CPU. The event explicitly states 'Insufficient cpu', indicating a resource shortage rather than a taint issue. Taints and tolerations are separate from resource-based scheduling.
- ✗
The pod's CPU limit is set too low, causing the scheduler to reject it.
Why it's wrong here
CPU limits are enforced at runtime by the kubelet and do not affect scheduling decisions. The scheduler only considers requests when placing pods. A low CPU limit would not cause a Pending state due to insufficient CPU; it would only throttle the container if it exceeds the limit.
- ✓
The pod's CPU request exceeds the allocatable CPU on any node.
Why this is correct
The scheduler reports insufficient CPU on all nodes, meaning no node has enough allocatable CPU to satisfy the pod's CPU request. This occurs when 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 reduced.
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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.