Troubleshooting Pod Pending State: Node Memory Pressure
An admin runs 'kubectl get pods' and sees a pod in 'Pending' state for a long time. 'kubectl describe pod' shows '0/1 nodes are available: 1 node has memory pressure'. Which is the most likely cause?
Quick Answer
The answer is that the node is under memory pressure and cannot admit the pod. This is correct because when a Kubernetes node’s kubelet detects memory pressure, it sets a corresponding condition that triggers eviction thresholds, causing the scheduler to refuse admission for new pods—except those with a Guaranteed QoS class—to prevent further resource exhaustion. On the Certified Kubernetes Administrator CKA exam, this scenario tests your understanding of kubelet node conditions and pod scheduling constraints, often appearing as a trap where candidates mistakenly blame resource requests or taints. A common memory tip is to recall that “memory pressure” means the node is protecting itself, not that the pod lacks resources; the pod stays Pending because the node actively rejects new workloads. Remember: pressure blocks admission, not resources.
⚠ Common exam trap
CNCF often tests the distinction between different node pressure conditions (memory vs. disk vs. PID) and their corresponding error messages, so candidates must recognize that 'memory pressure' is a specific kubelet condition, not a generic resource shortage.
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 node is under memory pressure and cannot admit the pod.
The '0/1 nodes are available: 1 node has memory pressure' message in `kubectl describe pod` indicates that the kubelet on the node has set a memory pressure condition, which triggers eviction thresholds. When a node is under memory pressure, the kubelet refuses to admit new pods (except those with QoS class Guaranteed) to prevent further resource exhaustion, leaving the pod stuck in Pending state. This matches option C exactly.
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 node's disk is full.
Why it's wrong here
The scheduler's message names memory pressure, not DiskPressure, so a full node disk is unrelated to this scheduling failure. Disk pressure is tempting because it is a genuine node condition that also renders a node unschedulable, but it would appear explicitly in the describe output.
- ✗
The pod's image pull secret is missing.
Why it's wrong here
A missing image pull secret causes ImagePullBackOff or ErrImagePull after scheduling, not a Pending pod with a node-fit message. It is tempting because image pull failures are a common cause of pods never starting, but they surface as container waiting states, not scheduler predicates.
- ✓
The node is under memory pressure and cannot admit the pod.
Why this is correct
The scheduler's filter plugin rejects nodes reporting MemoryPressure, so the pod stays Pending with the '0/1 nodes are available' message. The node cannot admit new pods until memory pressure clears or the pod requests are reduced.
- ✗
The pod requires more CPU than any node can provide.
Why it's wrong here
The scheduler reports memory pressure, meaning the node lacks allocatable memory; insufficient CPU would produce an Insufficient cpu message instead. CPU shortfalls are tempting because they are the other common resource-based scheduling failure, and both appear as Pending pods with node-fit errors.
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Same concept, more angles
1 more way this is tested on CKA
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. An admin runs 'kubectl get pods' and sees a pod in the 'Pending' state. Which is the most likely cause?
medium- A.The pod has been deleted
- B.The pod is waiting for a container to start
- ✓ C.The pod cannot be scheduled due to insufficient resources
- D.The container image is invalid
Why C: 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'.
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.