KCNA Kubernetes Fundamentals Practice Question
A developer creates a Deployment with 3 replicas. The developer runs 'kubectl get pods' immediately after creation and sees that only 1 pod is in Running state, and the other 2 are Pending. What is the most likely reason for this?
⚠ Common exam trap
CNCF often tests the distinction between Pod lifecycle phases — Pending means scheduling failure, not image or runtime issues — so candidates mistakenly associate Pending with image pull errors or node problems rather than resource insufficiency.
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 cluster does not have enough resources (CPU/memory) to schedule the additional pods
When a Pod remains in Pending state, it indicates that the scheduler cannot find a suitable node to place it. The most common cause is insufficient cluster resources (CPU or memory) to accommodate the additional Pods, as the scheduler checks node allocatable resources against Pod resource requests. With 2 out of 3 Pods pending, the cluster likely has enough resources for only one replica, leaving the others 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 cluster does not have enough resources (CPU/memory) to schedule the additional pods
Why this is correct
Pending means the scheduler cannot bind the pod to a node. With 3 replicas requested, insufficient allocatable CPU or memory across nodes leaves the extra pods unschedulable, so they remain Pending rather than failing or restarting.
- ✗
The Deployment's YAML has a syntax error
Why it's wrong here
A YAML syntax error would prevent the Deployment being created at all, so no pods would appear; here one pod runs, proving the manifest parsed. Syntax validation matters when applying manifests, but Pending pods indicate the scheduler cannot place them, not malformed configuration.
- ✗
The container image is not available on the worker nodes
Why it's wrong here
A missing image produces ImagePullBackOff or ErrImagePull, not Pending, because the pod must first be scheduled to a node before pulling. Image availability is the correct diagnosis when pods are assigned to nodes but containers cannot start.
- ✗
The kubelet on the node is not running
Why it's wrong here
A stopped kubelet would affect every pod on that node, yet one pod is Running; Pending means the scheduler has not bound the pods to a node at all. Kubelet troubleshooting applies when pods on a specific node fail to start, not when replicas remain unscheduled.
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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.