CNAME setting and processing in NNS

[roman-khimov]

I'm not sure NNS supports CNAME properly now, the behavior allows to set CNAME along with other types (like A or AAAA) and at the same time any non-CNAME record overrides CNAME in resolve. I don't think it's expected if we're roughly following DNS logic:
https://datatracker.ietf.org/doc/html/rfc1034#section-3.6.2
https://datatracker.ietf.org/doc/html/rfc2181#section-10.1

[erikzhang]

I know that CNAME records and A or AAAA records cannot coexist. But if they are checked every time, additional GAS will be consumed. Do you think it is necessary?

[roman-khimov]

We'll inevitably have misconfigured names otherwise. We can of course say that it's a user's problem, but preventing it seems a bit better to me. At the same time we'll have to use Find again probably and yes, it's somewhat expensive.