.internal is ICANN and not (yet?) an IETF RFC:
* https://en.wikipedia.org/wiki/.internal
Other special use domains:
* https://en.wikipedia.org/wiki/Special-use_domain_name
* https://en.wikipedia.org/wiki/Top-level_domain#Reserved_doma...
.internal is ICANN and not (yet?) an IETF RFC:
* https://en.wikipedia.org/wiki/.internal
Other special use domains:
* https://en.wikipedia.org/wiki/Special-use_domain_name
* https://en.wikipedia.org/wiki/Top-level_domain#Reserved_doma...
Looking at your links, subjective and legacy considerations aside, .alt per RFC 9476[1] seems as good a choice as .lan.
Personally, I just use a registered domain for this purpose, as they're cheap enough to not care (last I checked, I pay $10–20/domain/year for registrations, depending on registrar and TLD, and $0.21/zone/month for hosting public zones on Google Cloud).
[1] https://www.rfc-editor.org/rfc/rfc9476