Ehh, it's actually a topic for a yet-unfinished article of mine, but note that I pointed that "us-east-1 lambda service" is still a pet. In the case you descri

Ehh, it's actually a topic for a yet-unfinished article of mine, but note that I pointed that "us-east-1 lambda service" is still a pet. In the case you described, whatever drives the replacement system is the pet - the so-called cattle are just "components" that became interchangeable for the bigger "pet" system. As another commented called it, you need good names at the edge - where the edge for me is the level where you care about the system. We used to care about individual components of a computer and those would be effectively "pets" of the time. Nowadays, you do not give name to a DIMM in your server nor take extra care to ensure it works. And so on, till you reach the level you actually have to care, and that's where you need to name it (IMO) because that's your pet, even if it's composed of what people call cattle. As for hostnames matching functions - I found much more use when making hostnames reflect basic type of hw and physical location, and would keep the name as long as the location didn't change. The rest depended on what functions were currently applied to the machine.