KCNA Cloud Native Observability Practice Question
A Kubernetes operator wants to view real-time CPU and memory usage of pods and nodes in a cluster using kubectl top. Which component must be installed and running in the cluster for this command to work?
⚠ Common exam trap
It's easy for candidates to confuse general monitoring tools like Prometheus with the specific component that backs the kubectl top command.
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
✓
metrics-server
kubectl top retrieves metrics from the Kubernetes Metrics API, which is implemented by the metrics-server. The metrics-server collects resource usage data from Kubelets and makes it available through the API. Other tools like Prometheus or kube-state-metrics serve different purposes and do not power kubectl top, so metrics-server is the correct component to install.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Prometheus
Why it's wrong here
Prometheus is a powerful monitoring system that can scrape and store metrics, but kubectl top does not query Prometheus. It relies on the Kubernetes Metrics API, which is served by metrics-server. While Prometheus can provide similar data, it requires additional configuration and is not the component that enables kubectl top functionality.
- ✗
kube-state-metrics
Why it's wrong here
kube-state-metrics generates metrics about the state of Kubernetes objects, such as deployments and pods, but it does not provide real-time resource usage like CPU and memory. It listens to the Kubernetes API and exposes metrics for scraping, but kubectl top does not use it. Therefore, it does not satisfy the requirement for viewing live usage.
- ✓
metrics-server
Why this is correct
The metrics-server is a cluster-wide aggregator of resource usage data. It collects metrics from Kubelets and exposes them via the Metrics API, which kubectl top uses to display current CPU and memory usage for pods and nodes. Without metrics-server, kubectl top returns an error indicating that metrics are not available, so it is the required component.
- ✗
OpenTelemetry Collector
Why it's wrong here
The OpenTelemetry Collector is a vendor-neutral agent for receiving, processing, and exporting telemetry data. It can collect metrics, but it is not integrated with the Kubernetes Metrics API that kubectl top uses. Installing it would not enable kubectl top; instead, metrics-server is specifically designed to provide the resource metrics API for this purpose.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CNCF exam blueprint
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