It’s Not DNS (It’s MTU): Debugging Kubernetes Ingress

This is Part 3 of the Rack2Cloud Diagnostic Series, where we debug the silent killers of Kubernetes reliability. The Series: Part 1: ImagePullBackOff: It’s Not the Registry (It’s IAM) Part 2: The Scheduler is Stuck: Debugging Pending Pods Part 3: It’s Not DNS (It’s MTU): Debugging Ingress (You are here) Part 4: Storage Has Gravity (Debugging PVCs) You deploy your application. The pods are Running . kubectl port-forward works perfectly. You open the public URL, expecting success. 502 Bad Gateway. Or maybe: 504 Gateway Timeout upstream prematurely closed connection connection reset by peer no healthy upstream Welcome to the Networking Illusion . In Kubernetes, “Network Connectivity” is a stack of lies. The error message you see is rarely the error that happened. This is the Rack2Cloud Guide to debugging the space between the Internet and your Pod. The False Reality Stack (The “Bridge” Lie) Engineers often think of Ingress as a simple bridge: Traffic hits the Load Balancer and goes to the