CKA Practice Question: Cluster Architecture, Installation and Configuration
An admin runs 'kubectl get pods' and sees a pod in the 'Pending' state. Which is the most likely cause?
⚠ Common exam trap
CNCF often tests the distinction between pod states: candidates confuse 'Pending' with image-related issues, but 'Pending' specifically means the pod has not been scheduled yet, whereas image errors occur after scheduling.
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 cannot be scheduled due to insufficient resources
A pod in 'Pending' state indicates that the pod has been accepted by the Kubernetes API server but is not yet running. The most common cause is that the scheduler cannot find a node that satisfies the pod's resource requests (CPU, memory) or other scheduling constraints (taints, node selector, affinity rules). This results in the pod remaining unscheduled, hence 'Pending'.
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 been deleted
Why it's wrong here
A pod that has been deleted is removed from the cluster's etcd state and will no longer appear in the default kubectl get pods output. If the pod were in the Pending phase, it would still be present and visible, so deletion cannot explain the observed state. At most, a deleted pod that is mid-graceful-termination would show as Terminating, not Pending.
- ✗
The pod is waiting for a container to start
Why it's wrong here
The Pending phase specifically means the pod has been accepted by the API server but has not yet been scheduled to a node, so no containers have been created. If the kubelet were pulling an image or creating containers, the pod would transition to the ContainerCreating phase. Thus, waiting for a container to start is an occurrence after scheduling and is not reflected as Pending.
- ✓
The pod cannot be scheduled due to insufficient resources
Why this is correct
The Pending phase most commonly indicates that the scheduler cannot find a suitable node to place the pod. The scheduler evaluates resource requests (CPU, memory, ephemeral storage) against the allocatable capacity and remaining availability of each node; if every node has insufficient available resources, the pod remains unscheduled and stuck in Pending. This is typically confirmed by describing the pod and observing events such as FailedScheduling.
- ✗
The container image is invalid
Why it's wrong here
An invalid container image is only detected after a pod is scheduled and the kubelet attempts to pull that image from the registry. This results in errors like ImagePullBackOff or ErrImagePull, which occur in the Running or ContainerCreating phases. Since a Pending pod has not yet been assigned to a node, the image is never pulled, so an invalid image cannot be the reason for Pending.
Go deeper
Related to this question
Learn chapter
Kubernetes Architecture Overview
Key term
kubectl Command Reference
kubectl is the command-line tool used to interact with and manage Kubernetes clusters by sending commands to the Kubernetes API.
Key term
Network Policies
A Kubernetes resource that controls how pods communicate with each other and with other network endpoints, acting as a firewall for pod-to-pod traffic.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CKA 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 CKA exam.