Just what *is* a hostname (rfc952/1123, etc)

[Mark_Andrews at isc.org]

> 
> On Wed, Jan 23, 2002 at 03:44:43PM +0000, Barry Margolin wrote:
> 
> > David Carmean  <dlc-bu at halibut.com> wrote:
> 
> [snip]
> 
> > >So far I haven't been able to figure out from the RFCs whether a 
> > >hostname is just the leftmost label in a domain name, or whether 
> > >the *entire* domain name (fully-qualified or relative) must be 
> > >considered subject to the RFC952/1123 restrictions?
> > 
> > What difference does it make?  IIRC, the rules about hostnames apply to
> > each label, not the fully-qualified name.
> 
> It seems to be perfectly legal to create a domain named "foo_b#r&.com.", 
> if I'm reading RFC2181 correctly; the question is whether the name of 
> any node in the entire subtree below that zone cut can be a legal 
> Internet hostname.

	None can be a legal hostname.

> 
> The practical matter is that I'm writing some tools and I want to 
> get my t's crossed and my i's dotted [0] correctly, so-to-speak.
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at isc.org