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From: Nobody <nobody@nowhere.com>
Subject: Re: Validating string for FDQN
Date: Tue, 07 Jun 2011 21:46:04 +0100
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On Tue, 07 Jun 2011 15:52:05 +1000, Chris Angelico wrote:

>> [1] If a hostname ends with a dot, it's fully qualified.
> 
> Outside of BIND files, when do you ever see a name that actually ends
> with a dot?

Whenever it is entered that way.

This may be necessary on complex networks with local subdomains, i.e.
where resolv.conf has "options ndots:2". E.g. "foo.it" might resolve to
"foo.it.bar.edu" (in bar.edu's IT department's subdomain), requiring a
trailing dot if you want the Italian site "foo.it".

The canonical real-world example of this used to be foo.cs resolving to
foo.cs.berkeley.edu (UCB Comp. Sci. department), but ever since .cs split
into .cz and .sk it's no longer ambiguous.