CKA Troubleshooting Practice Question
You are troubleshooting a node that is in 'NotReady' state. Which command should you use to check the kubelet logs for errors?
⚠ Common exam trap
Test-takers frequently confuse control plane components (kube-apiserver, kube-controller-manager) with node-level components, or mistakenly think the container runtime (Docker) is the primary source of node readiness logs, when in fact the kubelet is the authoritative agent for node status.
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
✓
journalctl -u kubelet
The kubelet is the primary node agent that communicates with the control plane and manages pods. When a node is in 'NotReady' state, checking the kubelet logs is the first step to diagnose issues such as certificate errors, resource pressure, or network problems. The command `journalctl -u kubelet` retrieves logs from the systemd unit for the kubelet service, which is the correct way to view its output on systems using systemd.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
journalctl -u kubelet
Why this is correct
When a node is in a `NotReady` state, it signifies that the Kubelet, the agent running on the node, is unable to register itself with the API server or report its health status. The Kubelet is responsible for managing pods, reporting node status, and executing container operations. Therefore, examining the Kubelet's logs via `journalctl -u kubelet` provides direct insight into why it might be failing to communicate, experiencing resource issues, or encountering problems with the container runtime, making it the most critical first step for diagnosis.
- ✗
journalctl -u docker
Why it's wrong here
While Docker (or any container runtime like containerd or CRI-O) is essential for running containers on a node, its logs are not the primary place to start when the node itself is `NotReady`. The Kubelet is the component that communicates the node's health to the Kubernetes control plane. If the Kubelet itself is failing to start, communicate, or detect the runtime, its own logs will reveal that failure, even before delving into the container runtime's specific operational issues.
- ✗
journalctl -u kube-apiserver
Why it's wrong here
The `kube-apiserver` is a central component of the Kubernetes control plane, typically running on master nodes, responsible for exposing the Kubernetes API. While the Kubelet communicates *with* the API server, checking the API server's logs would primarily reveal issues with the control plane itself or requests *from* the Kubelet, not the root cause of a `NotReady` state on a specific worker node. The problem is localized to the worker node, making its local Kubelet logs the appropriate diagnostic starting point.
- ✗
journalctl -u kube-controller-manager
Why it's wrong here
The `kube-controller-manager` runs various controllers that watch the shared state of the cluster through the API server and make changes to move the current state towards the desired state. For instance, the Node Controller handles node registration and monitors node health. While it might mark a node as `NotReady` based on Kubelet's reports, its logs would only show *that* it detected a problem, not *why* the Kubelet on the specific node is failing. Troubleshooting a `NotReady` node requires investigating the agent *on that node* directly.
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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.