That's an Internet Draft, not a standard or even at least a published RFC. An Internet Draft cannot be used Internet-Drafts as reference material or cited as an

That's an Internet Draft, not a standard or even at least a published RFC. An Internet Draft cannot be used Internet-Drafts as reference material or cited as anything other than "work in progress." There are some more reserved domains in RFC 6761 (https://datatracker.ietf.org/doc/html/rfc6761 https://datatracker.ietf.org/doc/html/rfc6761) though: - .test (Application software SHOULD NOT recognize test names as special, and SHOULD use test names as they would other domain names. [...] Caching DNS servers SHOULD recognize test names as special and SHOULD NOT, by default, attempt to look up NS records for them, or otherwise query authoritative DNS servers in an attempt to resolve test names. Instead, caching DNS servers SHOULD, by default, generate immediate negative responses for all such queries.) - .localhost (Users are free to use localhost names as they would any other domain names. Users may assume that IPv4 and IPv6 address queries for localhost names will always resolve to the respective IP loopback address.) - .invalid (Users are free to use "invalid" names as they would any other domain names. Users MAY assume that queries for "invalid" names will always return NXDOMAIN responses. Name resolution APIs and libraries SHOULD recognize "invalid" names as special and SHOULD always return immediate negative responses. Name resolution APIs SHOULD NOT send queries for "invalid" names to their configured caching DNS server(s).) - .example, .example.com, .example.net (Users SHOULD understand that example names are reserved for use in documentation.) Unfortunately, none of these address the same needs as .internal would.