CKA Troubleshooting Practice Question

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 API server is down or not reachable

  Why this is correct

  The kube-controller-manager is a client of the Kubernetes API server; every control loop (deployment, replicaset, namespace, service account) lists objects through the API. A repeated 'failed to list' or connection-refused error means the API server is either down, unresponsive, or unreachable from the controller node. This is the only condition that explains the manager's own client logs while the manager process itself remains running.

• ✗

  The kube-controller-manager is not running

  Why it's wrong here

  If the kube-controller-manager were not running, it could not emit any controller errors at all — the log entries are produced by that very process after it has started. The error pattern shows it is alive but cannot establish or maintain its client connection to the API server. A stopped or crash-looping manager would instead be diagnosed by checking static pod status or systemd unit, not by seeing its own connection errors.

• ✗

  The kubelet on the controller node is down

  Why it's wrong here

  The controller-manager never reads pods from the local kubelet; it watches pod metadata through the API server and uses the kubelet only as the eventual executor on worker nodes. A kubelet outage on the control-plane node could stop the static pod that hosts the manager, but the specific 'failed to list' errors indicate an outbound API connection problem, not a local container runtime issue. Therefore kubelet downtime cannot directly cause the API server to become unreachable from the controller-manager.

• ✗

  The scheduler is overloading the API server

  Why it's wrong here

  An overloaded scheduler would slow down the API server with frequent binding and pod-placement requests, producing latency, timeouts, or 429 rate-limit responses — not repeated client-side connection failures. Moreover, the scheduler is a separate binary whose load does not break the controller-manager's own watch streams; each control-plane component has its own independent API client connection. The 'failed to list' errors are specific to the controller-manager's inability to reach the API server, not to global pressure from another component.