CKAD Application Observability and Maintenance Practice Question
A pod is stuck in the Pending state. You run 'kubectl describe pod pod-name' and see the event: '0/4 nodes are available: 1 node had taint {node-role.kubernetes.io/control-plane: }, that the pod didn't tolerate, 3 nodes had taint {node.kubernetes.io/disk-pressure: }, that the pod didn't tolerate.' What is the MOST likely cause?
⚠ Common exam trap
Watch out — candidates often confuse taint-based scheduling failures with resource insufficiency (CPU/memory) and select options B, C, or D, even though the event explicitly names taints as the cause.
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 nodes have disk pressure and the pod lacks tolerations
The event explicitly states that 1 node had a control-plane taint and 3 nodes had a disk-pressure taint, all of which the pod did not tolerate. The pod remains in Pending state because no node can schedule it until either the taints are removed or the pod includes matching tolerations. This directly matches the condition described in the event.
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 nodes have disk pressure and the pod lacks tolerations
Why this is correct
The `kubectl describe` output would show an event indicating that each node has a taint such as `node.kubernetes.io/disk-pressure`. Because the pod defines no tolerations for that taint, the scheduler filters out those nodes, leaving the pod Pending. Disk pressure is a node condition that the kubelet automatically encodes as a taint, and pods must explicitly tolerate it to be scheduled. This matches the event description exactly, unlike resource-based failures.
- ✗
The pod has a resource request that exceeds node capacity
Why it's wrong here
If the pod's resource requests exceeded the allocatable capacity of every node, the scheduler would report an `Insufficient cpu` or `Insufficient memory` event in `kubectl describe`, not a taint-based rejection. The provided event specifically mentions disk-pressure taints, so the cause is not a resource request mismatch. Additionally, taints and tolerations are a separate scheduling mechanism from resource requests; a pod with oversized requests might remain Pending, but the event name and reason would differ from the one described.
- ✗
The nodes have insufficient CPU
Why it's wrong here
Insufficient CPU is a resource-based scheduling failure that would surface as an event such as `Insufficient cpu` in the describe output, not as a taint. Kubernetes creates taints for conditions like DiskPressure or MemoryPressure, but ordinary CPU saturation does not produce a taint on a node. Since the event references disk-pressure, the Pending state cannot be attributed to a lack of CPU capacity on the nodes.
- ✗
The nodes have insufficient memory
Why it's wrong here
Insufficient memory would generate a `MemoryPressure` node condition and a corresponding `node.kubernetes.io/memory-pressure` taint, not the disk-pressure taint mentioned in the event. The scheduler would also log an `Insufficient memory` event if the pod's memory request could not be met, but the describe output points to disk pressure. Therefore, memory insufficiency is not the reason the pod remains Pending.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CKAD 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 CKAD exam.