Requests, Limits, and Quality of Service — Who Survives When a Node Runs Out

You have set resources.requests and resources.limits since Day 6 without unpacking what they really do. The relationship between them silently assigns every Pod a Quality of Service class — Guaranteed, Burstable, or BestEffort — and that class decides who the kubelet sacrifices first when a node runs out of memory. Day 25 makes all three classes concrete, reads the kernel's actual kill-priority knob out of each Pod, then proves the two failure modes you must never confuse: a CPU limit throttles (and never kills), a memory limit kills (OOMKilled, exit 137).