CKA Troubleshooting Practice Question
You are troubleshooting a node that is 'NotReady'. Which THREE of the following are possible causes? (Choose three.)
⚠ Common exam trap
Candidates often confuse node conditions like 'DiskPressure' or 'MemoryPressure' with the 'NotReady' status, but these conditions do not change the 'Ready' status unless the kubelet itself fails to report.
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 kubelet cannot contact the API server
The kubelet is the primary node agent that communicates with the API server to report node status, heartbeats, and pod lifecycle events. If the kubelet cannot reach the API server (e.g., due to network partition, TLS certificate issues, or API server downtime), it cannot send the periodic NodeStatus updates, and the control plane marks the node as 'NotReady' after the `node-monitor-grace-period` (default 40 seconds) expires.
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 kubelet cannot contact the API server
Why this is correct
The kubelet is responsible for registering the node with the API server and continuously reporting its health and status. If the kubelet loses its ability to communicate with the API server, it cannot send its periodic heartbeats or update the node's conditions. After a default timeout period, the control plane will mark the node as NotReady because it has stopped receiving updates, indicating a potential issue with the node's availability or connectivity.
- ✓
The kubelet service is stopped
Why this is correct
The kubelet is the primary agent running on each node, managing pods and reporting node status. If the kubelet service itself stops running, it ceases all operations, including sending crucial periodic heartbeats to the Kubernetes API server. Without these regular heartbeats, the control plane will eventually time out and update the node's status to NotReady, indicating that the node is no longer responsive or operational from Kubernetes' perspective.
- ✗
The node has disk pressure
Why it's wrong here
Disk pressure is a specific node condition indicating that the node's disk space is running low, which can trigger eviction of pods to free up resources. While it affects pod scheduling and can lead to performance issues, it does not inherently cause the node to transition to a NotReady state. A node experiencing disk pressure typically remains Ready but with the DiskPressure=True condition, signaling a resource constraint rather than a complete loss of functionality or connectivity.
- ✗
A pod on the node is consuming excessive memory
Why it's wrong here
A single pod consuming excessive memory will likely be terminated by the kernel's Out-Of-Memory (OOM) killer or by Kubernetes if it exceeds its memory limits. While this affects the specific pod, it is an isolated event within the node's resource management. The node itself, and the kubelet running on it, typically remain healthy and Ready, continuing to report their status to the API server, unless the excessive memory consumption is so severe it destabilizes the entire operating system.
- ✓
The network plugin (e.g., Calico, Flannel) is not running
Why this is correct
The Container Network Interface (CNI) plugin, such as Calico or Flannel, is crucial for establishing network connectivity for pods and often for the node's ability to communicate within the cluster. If the network plugin is not running or misconfigured, the kubelet might lose its network path to the API server, preventing it from sending heartbeats and status updates. This loss of communication will ultimately lead to the control plane marking the node as NotReady due to unresponsiveness.
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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.