CKA Practice Question: Cluster Architecture, Installation and Configuration
An administrator runs 'kubectl get nodes' and sees that one node is in the 'NotReady' state. Which component should be checked FIRST to diagnose the issue?
⚠ Common exam trap
CNCF often tests the misconception that the kube-controller-manager or kube-apiserver is the root cause of node unreadiness, but the trap here is that the kubelet is the sole component responsible for reporting node health, and its failure is the most direct cause of a 'NotReady' state.
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
✓
kubelet on the worker node
The kubelet is the primary node agent that runs on every worker node and is responsible for registering the node with the cluster and periodically reporting its status via NodeStatus updates. When a node is in 'NotReady' state, it means the kubelet has failed to send heartbeats or report readiness to the control plane, typically due to a crash, misconfiguration, or resource exhaustion. Checking the kubelet's logs and service status (e.g., 'systemctl status kubelet' or 'journalctl -u kubelet') is the first diagnostic step because it directly controls node health reporting.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
kubelet on the worker node
Why this is correct
The kubelet is the essential agent running on each worker node, responsible for registering the node with the control plane and continuously reporting its health and status to the API server via heartbeats. If the kubelet process fails, crashes, or loses network connectivity on a specific worker node, it stops sending these crucial heartbeats. Consequently, the Node Controller on the control plane will eventually mark that particular node as 'NotReady' because it is no longer receiving status updates from its designated agent.
- ✗
kube-apiserver on the control plane
Why it's wrong here
The kube-apiserver acts as the central communication hub for the entire Kubernetes cluster, processing all REST requests. If the kube-apiserver itself were experiencing issues or was down, `kubectl get nodes` commands would likely fail entirely or show all nodes as unreachable, not just a single worker node. A single node appearing 'NotReady' while other nodes are healthy indicates that the API server is functioning correctly and receiving status updates from the healthy nodes, but not from the problematic one.
- ✗
kube-controller-manager
Why it's wrong here
The kube-controller-manager runs various controllers, including the Node Controller, which is responsible for monitoring the health of nodes. While the Node Controller *marks* a node as 'NotReady' after a timeout if it stops receiving heartbeats from the kubelet, the controller-manager does not *cause* the kubelet to fail. Its failure would manifest as broader cluster management issues, such as pods not being scheduled or replica sets not being maintained, rather than directly causing a single node's kubelet to stop reporting.
- ✗
etcd cluster health
Why it's wrong here
etcd serves as the highly available, consistent key-value store for all Kubernetes cluster data, including node status, pod definitions, and configuration. If the etcd cluster were unhealthy or experiencing issues, the API server would be unable to read or write cluster state effectively. This would lead to widespread cluster instability, affecting the perceived status of all nodes, preventing new operations, or causing existing resources to become unmanageable, rather than isolating the problem to just one worker node.
Go deeper
Related to this question
Learn chapter
Configuring Core Cluster Components
Key term
kubectl Command Reference
kubectl is the command-line tool used to interact with and manage Kubernetes clusters by sending commands to the Kubernetes API.
Key term
Kubernetes Node Roles
Kubernetes Node Roles are labels assigned to machines in a cluster that define whether a node runs application containers (worker) or manages the cluster (control plane).
About these practice questions
One of 302 original CKA practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
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.