cni

The single most common Kubernetes interview question, and the one where a vague answer is most obvious. Every stage you name is a place the interviewer can ask you to debug.

The question that finds out whether you know Kubernetes networking or just use it. The model has three rules and everything about CNI follows from them.

Cilium became the default CNI on major managed platforms for a reason that is mechanical rather than fashionable. The iptables datapath degrades with service count, and eBPF replaces a linear scan with a map lookup.

Same-node good, cross-node bad is not a random clue, it is nearly a diagnosis. One short decision tree separates overlay reachability, encapsulation blocks, MTU and policy.