KCNA Kubernetes Fundamentals Practice Question
You notice that a pod is in 'Pending' state for a long time. Which of the following is the most likely cause?
⚠ Common exam trap
A common exam trap is confusing scheduling failures (Pending) with runtime failures (CrashLoopBackOff, ImagePullBackOff). Candidates often mistake probe or image issues as causes of the Pending state, but these occur after the pod is scheduled.
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
✓
No node has enough CPU or memory to meet the pod's requests.
A pod remains in 'Pending' state when the scheduler cannot find a node that satisfies its resource requests. The most common reason is insufficient CPU or memory capacity across all available nodes, preventing the pod from being bound to a node. Unlike probe failures or missing images, which cause 'Running' or 'ImagePullBackOff' states, resource constraints block scheduling entirely.
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 liveness probe is failing.
Why it's wrong here
A failing liveness probe restarts a container that is already running; it cannot cause Pending, which occurs before any container starts. Liveness probes are the right answer when a Running pod repeatedly restarts, the symptom this option actually describes.
- ✓
No node has enough CPU or memory to meet the pod's requests.
Why this is correct
The scheduler leaves a pod Pending when no node satisfies its resource requests, since insufficient allocatable CPU or memory prevents binding. Image pull failures or crash loops instead produce ErrImagePull or CrashLoopBackOff, so resource shortfall is the likely cause.
- ✗
The pod's readiness probe is not configured.
Why it's wrong here
A missing readiness probe leaves the pod Running but unready; it does not prevent scheduling, so the pod would not remain Pending. Readiness probes are genuinely relevant when a Running pod receives no traffic, which is the scenario where this option would apply.
- ✗
The container image does not exist.
Why it's wrong here
A nonexistent image produces ImagePullBackOff or ErrImagePull after scheduling succeeds, so the pod leaves Pending. It is tempting because image problems are a frequent pod failure, but they manifest as pull errors on a node, not as an unscheduled pod.
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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. You run 'kubectl get pods' and see a pod with status 'Pending'. Which is the most likely cause?
medium- A.The pod's container has crashed
- ✓ B.The scheduler cannot find a node that meets the pod's resource requirements
- C.The container image is not found
- D.The pod has been deleted by a controller
Why B: A pod with status 'Pending' indicates that the pod has been accepted by the cluster but is not yet running. The most common cause is that the Kubernetes scheduler cannot find a node that satisfies the pod's resource requests (CPU, memory) or other constraints (node selector, taints/tolerations, affinity rules). The scheduler continuously evaluates nodes and if none match, the pod remains in Pending state until a suitable node becomes available.
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.