Is there a standard or RFC saying NS records are not to be pointed to zone apex (with appropriate glue in parent zone)?
For example:
test.test. IN NS test.test.
test.test. IN A 192.0.2.1
Is there a standard or RFC saying NS records are not to be pointed to zone apex (with appropriate glue in parent zone)?
For example:
test.test. IN NS test.test.
test.test. IN A 192.0.2.1
You certainly can create nameservers with the name being the zone name (apex), it works and is used by some. There is no specific reason to prohibit that, and hence I don't think you can find an RFC forbidding that because, technically, there is nothing wrong there per se.
However, expect some major head scratching at least. Doing things like that will expose you to many bugs at both registries and registrars that won't accept, by error, a nameserver with such a name, and also remember that you will, like for any glue, need to update the IP address at registry as needed (a regular case of DNS errors, which points towards avoiding glues like that when possible most often), and have more difficulties in updating this specific domain.
In short, as I see little benefits in those setups and many possible drawbacks this is certainly something I suggest to avoid, outside of local tests or being an absolute master in DNS and domain name management.
The subject is however mentioned is the most up to date standardized document on DNS things aka RFC 8499, as such:
- In-domain: a modifier to describe a name server whose name is either subordinate to or (rarely) the same as the owner name of the NS resource records. An in-domain name server name needs to have glue records or name resolution fails. For example, a delegation for "child.example.com" may have "in-domain" name server name "ns.child.example.com".
Note the (emphasis mine): "or (rarely) the same as the owner name of the NS resource records."