Re: DNS and subdomains

[William Herrin <bill () herrin us>]

On Fri, Feb 28, 2025 at 9:11 AM Jay <mysidia () gmail com> wrote:
> Every subdomain is in fact a domain name.

Hi Jay,

Not necessarily.

Remember my example cat.p.dirtside.com? P.dirtside.com is a subdomain
of dirtside.com. It's an administrative grouping of domain names that
have a particular characteristic. However, p.dirtside.com is NOT a
domain name. It has no DNS records of its own. Only subsidiaries like
cat.p.dirtside.com exist and have DNS records.

"Subdomain" has some funky contradictions to it, some of which can
only be resolved with administrative knowledge about the DNS zone
they're a part of. That's what makes them a less than useful concept
for an outside observer trying to categorize a set of fully qualified
domain names (FQDNs).

Regards,
Bill Herrin


-- 
William Herrin
bill () herrin us
https://bill.herrin.us/