On Tue, Feb 25, 2025 at 07:36:16AM -0500, Harry Hoffman via NANOG <nanog@nanog.org> wrote a message of 168 lines which said:
> I had a thought similar to what Bill describes, that everywhere there's a > dot (.) there's a subdomain. This is true. But a sub-domain is not always delegated (not every domain is a zone). > to use the publicsuffix.org site to divine suffix and domain and > then consider everything to the left of that as a subdomain. I've > now updated my understanding. Sorry, but not yet. Every domain name is a subdomain, except the root (which has no parent). And not every domain name is a host name (saying that the DNS is "to translate names into IP addresses" is a gross simplification).
