Kubernetes Pod network issues are among the most common and frustrating problems for cluster operators. This guide presents a systematic diagnostic flow that covers two frequent scenarios: DNS resolution failures and cross-node communication anomalies. The approach starts with verifying Pod network basics—checking CNI plugin status, network policy rules, and service endpoints. For DNS issues, the flow includes examining CoreDNS pod logs, checking DNS configuration in Pod specs, and testing with debug containers. For cross-node problems, the methodology involves validating node network connectivity, checking kube-proxy rules, and inspecting tunnel or overlay configurations. This structured process helps operators reduce mean time to resolution (MTTR) by eliminating guesswork. While the original post is based on a specific case, the diagnostic steps are generic and applicable to any Kubernetes distribution. Operators can adopt this framework as a standard operating procedure for network troubleshooting.
This post outlines a step-by-step diagnostic process for Kubernetes Pod network issues, covering DNS resolution failures and cross-node communication problems. It provides a practical checklist for operators to isolate and resolve common network faults in production clusters.