CKA Troubleshooting Practice Question
You run 'kubectl top nodes' but get 'error: metrics not available yet'. What is the most likely 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 Metrics Server is not deployed
Metrics server is not deployed or not ready, so resource metrics are unavailable.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
kubectl top requires root access
Why it's wrong here
kubectl top does not require Unix root privileges; kubectl authenticates to the cluster using kubeconfig credentials and is governed by Kubernetes RBAC. A non-root user with a Role or ClusterRole permitting access to the metrics.k8s.io API can run kubectl top successfully. The error 'metrics not available' indicates that the metrics API has no data to return, not that the caller lacks OS-level permissions.
- ✗
Nodes have insufficient CPU
Why it's wrong here
Insufficient CPU on nodes does not prevent resource metrics from being reported. The Metrics Server is a lightweight pod or collection of pods that queries each kubelet's Summary API over HTTPS; kubelet continues to expose usage data even under heavy load. The absence of metrics output is a function of the Metrics Server not being present or not having collected data, not of node CPU starvation.
- ✓
The Metrics Server is not deployed
Why this is correct
The Metrics Server is an optional cluster component that aggregates resource usage from kubelets and exposes it through the metrics.k8s.io API, which kubectl top and the Horizontal Pod Autoscaler consume. In a standard kubeadm or vanilla cluster it is not installed by default, so kubectl top nodes fails with 'metrics not available' until the Metrics Server manifests are applied. Deploying the Metrics Server and allowing it time to collect its first metrics resolves the error.
- ✗
Kubelet is not running on nodes
Why it's wrong here
If the kubelet were truly not running on a node, the node would transition to NotReady and would likely be excluded from kubectl top output or generate a different error. The typical 'metrics not available' message appears even when all nodes are Ready, meaning kubelet is operational and reporting its Summary API to the API server. A missing Metrics Server is the primary cause of this symptom, not a stopped kubelet.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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