CKA Troubleshooting Practice Question
Which THREE of the following are common causes for a Pod to remain in Pending state? (Select THREE.)
⚠ Common exam trap
The CKA exam frequently tests your ability to troubleshoot Pod states. Remember that 'Pending' is a scheduling-phase state. If a Pod is Pending, the issue is almost always related to scheduling (resources, taints/tolerations, node selectors, affinity) or volume binding. Once a Pod is assigned to a node, failures will manifest as 'ImagePullBackOff', 'CrashLoopBackOff', or 'Failed', not 'Pending'.
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
✓
Insufficient CPU or memory resources in the cluster
Option A is correct because when no node has enough allocatable CPU or memory to satisfy the Pod's resource requests, the scheduler cannot place the Pod and it stays in Pending. Option B is correct because taints on nodes that the Pod does not tolerate cause the scheduler to reject those nodes, leaving the Pod unscheduled and Pending. Option C is correct because a PersistentVolumeClaim that is not yet bound to a PersistentVolume blocks scheduling of Pods that reference it, keeping them in Pending. Option D does not belong because OOMKilled is a container termination reason that occurs after the Pod has been scheduled and started, producing a CrashLoopBackOff or Error state rather than Pending. Option E does not belong because an image pull error happens during kubelet container creation after scheduling, resulting in ImagePullBackOff or ErrImagePull, not 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.
- ✓
Insufficient CPU or memory resources in the cluster
Why this is correct
When no node has enough allocatable CPU or memory to satisfy the Pod's resource requests, the kube-scheduler's filter phase rejects every candidate node, leaving the Pod unscheduled in Pending. This is the classic capacity-driven cause.
- ✓
Taints on nodes that are not tolerated by the Pod
Why this is correct
Taints on nodes repel Pods that lack matching tolerations, leaving the scheduler unable to place them, so the Pod remains Pending. This is one of the three common scheduling-failure causes alongside insufficient resources and unbound persistent volume claims.
- ✓
PersistentVolumeClaim is not bound to a PersistentVolume
Why this is correct
The kube-scheduler cannot place a Pod whose PersistentVolumeClaim remains unbound, because no PersistentVolume satisfies the claim's storage class, access mode or capacity request. The Pod stays Pending until binding succeeds, directly matching this listed cause.
- ✗
Container exits with OOMKilled
Why it's wrong here
OOMKilled describes a container terminated after starting because it exceeded its memory limit, so the Pod had already been scheduled and reached Running. It is tempting because memory pressure sounds like a scheduling concern, but Pending means no node has been assigned yet.
- ✗
Image pull error due to incorrect image name
Why it's wrong here
An incorrect image name causes ImagePullBackOff or ErrImagePull after the Pod is scheduled to a node, so the phase is Waiting, not Pending. It is tempting because the Pod never runs, but Pending specifically means the scheduler has not bound the Pod to any node.
Go deeper
Related to this question
Learn chapter
Troubleshooting Cluster and Node Issues
Key term
Pod Failure Troubleshooting
Pod failure troubleshooting is the process of identifying and resolving issues that cause Kubernetes pods to crash, restart, or become unavailable.
Key term
Persistent Volumes
A Persistent Volume is a piece of storage in a Kubernetes cluster that has been provisioned by an administrator and exists independently of any single pod that uses it.
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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.