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Re: RFC2396bis, qualified, a nit

From: Peter Koch <pk@TechFak.Uni-Bielefeld.DE>
Date: Thu, 27 Feb 2003 10:55:09 +0100
Message-Id: <200302270955.h1R9t9015617@grimsvotn.TechFak.Uni-Bielefeld.DE>
To: "Roy T. Fielding" <fielding@apache.org>
Cc: uri@w3.org

> Yep.  Theoretically speaking it matches the way BIND works, but I agree
> that it is better for parsers as
> >    qualified     = *( "." domainlabel ) [ "." toplabel "." ]
> Added to the list as 038-qualified.  Thanks.

In the DNS the trailing '.' is never part of the domain name. It is only
used in zone file format to explicitly declare a domain name as FQDN.
Also, it's currently true that TLD names do not start with digits, there's
nothing in 1123 (or 952) that would forbid this. Until 1123 was published,
a digit was not allowed as the first character of any label, but this was
what 1123 relaxed. The only remaining restriction in this direction is that
a hostname must not "look like" an IP (v4) address, i.e. it would be
unwise to have a TLD consisting of digits only.

I'd like to suggest that a hostname be either an FQDN (identified as such
by having at least one dot) or consist only of a single label. Everything
else is too dependent on the actual DNS searchlist strategy.
The only remaining ambiguity would be the TLD name used as a hostname in the
URL (of the 258 TLDs roughly a dozen, e.g. DK and TV have an A RR for the TLD
itself). For the sake of consistency that should be treated like a non-FQDN
first.  A trailing '.' should not be allowed.

Received on Thursday, 27 February 2003 04:56:57 UTC

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