KCNA Kubernetes Fundamentals Practice Question
A pod is stuck in 'Pending' state. After running 'kubectl describe pod', you see the event: '0/3 nodes are available: 3 Insufficient cpu'. What is the most likely cause?
⚠ Common exam trap
A common mistake in Kubernetes is confusing resource requests (used for scheduling) with resource limits (used for runtime enforcement). Candidates may incorrectly think a pod stuck in 'Pending' is due to exceeding a limit rather than an unsatisfied request.
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 available CPU on all nodes
The pod is stuck in 'Pending' state because the Kubernetes scheduler cannot find a node that satisfies the pod's resource requirements. The event '0/3 nodes are available: 3 Insufficient cpu' explicitly indicates that every node in the cluster lacks sufficient allocatable CPU capacity to meet the pod's CPU request. This means the sum of CPU requests across all pods on each node, plus the new pod's request, exceeds the node's CPU capacity, causing the scheduler to leave the pod unscheduled.
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's CPU request exceeds the available CPU on all nodes
Why this is correct
The scheduler reports insufficient CPU resources.
- ✗
The pod is exceeding its memory limit
Why it's wrong here
Memory issues cause OOMKilled, not pending.
- ✗
The network plugin is not installed
Why it's wrong here
Network plugin issues cause different errors (e.g., CrashLoopBackOff).
- ✗
The container image is too large
Why it's wrong here
Image size does not cause CPU insufficiency.
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Same concept, more angles
1 more way this is tested on KCNA
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A Pod has been in 'Pending' state for an unusual amount of time. Which of the following is a likely cause?
medium- A.The container image is invalid
- B.The Pod's liveness probe is failing
- ✓ C.The cluster does not have enough resources to schedule the Pod
- D.The Service pointing to the Pod is misconfigured
Why C: A Pod stuck in 'Pending' state indicates that the Pod has been accepted by the API server but has not been scheduled to a node. The most common cause is insufficient cluster resources (CPU, memory, or ephemeral storage) across all nodes, preventing the scheduler from finding a suitable node that meets the Pod's resource requests. The scheduler continuously evaluates nodes using predicates and priorities, and if no node passes the predicates (e.g., NodeResourcesFit), the Pod remains Pending.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.