CKA Certification Course 2025 - Day 58: Kubernetes Data Plane Troubleshooting Guide | CKA Course 2025

Day 58: Kubernetes Data Plane Troubleshooting Guide | CKA Course 2025 👉 GitHub Repository: https://github.com/CloudWithVarJosh/CKA-Certification-Course-2025 👉 CKA 2025 Playlist: https://youtube.com/playlist?list=PLmPit9IIdzwRjqD-l_sZBDdPlcSfKqpAt&si=1JNRkoNa75AOJx0o 👉 Kubernetes Projects: https://www.youtube.com/playlist?list=PLmPit9IIdzwSv2zwizysG6OwWUACpQFN0 Join the Channel to show your support: https://www.youtube.com/channel/UCaLKKEjj21ucnOYi45ZHwkw/join 📚 Welcome to Day 58! Today we fix the data plane CKA-style. You’ll learn how kubelet, the container runtime, CNI, kube-proxy, and CoreDNS work together—and how to spot and repair the most common breakages fast. We’ll use a 90-second triage, kubectl describe/events, journalctl, and crictl to diagnose, then apply the smallest fix and verify immediately. 🛠 What You’ll Learn in This Demo ✅ Node NotReady triage: kubelet stopped, swap ON, and cert/kubeconfig issues ✅ CNI not initialized: missing /etc/cni/net.d or CNI DaemonSet scaled down ✅ Service failures: endpoints empty / targetPort mismatch → ClusterIP curl fails ✅ DNS failures: CoreDNS down → nslookup kubernetes.default fails in pod ✅ Practical toolkit: kubectl get/describe/events, journalctl -u kubelet, crictl, and a quick netshoot/busybox pod for network checks ✅ Exam mindset: symptom-first “mystery mode,” minimal change, instant verification 💡 By the end of this lecture: You’ll have a repeatable playbook for data-plane issues: kubelet/CRI → CNI/IPs → Services/endpoints (kube-proxy) → DNS (CoreDNS)—plus clear fixes you can execute under time pressure in the CKA. 🔗 Stay Connected 👉 LinkedIn: https://linkedin.com/in/varun-joshi-2b516752 👉 GitHub: https://github.com/CloudWithVarJosh 💬 Got questions? Drop them in the comments — I reply to every single one. 👍 Like, share, and subscribe to follow the entire CKA 2025 series! ⏰ Timestamps 00:00:00 Introduction 00:01:03 Prerequisites 00:03:58 Data Plane Quick Tour 00:09:33 Cluster Overview 00:11:06 Scenario 1 — Node NotReady; new pods avoid the node 00:16:45 Scenario 2 — Node NotReady; pod exec/logs stall 00:24:40 Scenario 3 — Node NotReady; kubelet shows connection errors 00:29:28 Scenario 4 — Pods stuck ContainerCreating (no IP) 00:33:41 Scenario 5 — ClusterIP request fails (curl http://svc:port) 00:39:05 Scenario 6 — DNS lookup fails (nslookup kubernetes.default) 00:46:44 Outro & Next Steps 🔖 Hashtags #Kubernetes #CKA #CKA2025 #Troubleshooting #DataPlane #kubelet #CNI #kubeproxy #CoreDNS #containerd #DevOps #SRE #CloudWithVarJosh #CKACourse