Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!ncar!woods
From: woods@ncar.ucar.edu (Greg Woods)
Newsgroups: news.admin
Subject: Re: Registered sitenames
Message-ID: <94@ncar.ucar.edu>
Date: 5 Apr 88 03:54:03 GMT
References: <1590@sigma.UUCP> <4750002@hpscdc.HP.COM> <3191@hammer.TEK.COM> <90@ncar.ucar.edu> <2098@ho95e.ATT.COM>
Reply-To: woods@handies.UCAR.EDU (Greg Woods)
Organization: Scientific Computing Division/NCAR, Boulder CO
Lines: 21
Keywords: registered hostnames, domains, maps

In article <2098@ho95e.ATT.COM> wcs@ho95e.UUCP (46323-Bill.Stewart.<ho95c>,2G218,x0705,) writes:
>For instance, what if you have local machine named "b.ucar.edu", which you
>address locally as "b", and I register a machine named "b".
>If you get a mail message for "joe@b" or "b!joe", who do you send it to?

   You can't have a domain named "b", nor anything else that I could name
a machine here. All domains (except phony ones like "uucp") have at least
one period in them. This makes them clearly distinguishable from a local
machine name. Thus in your example, without question I send it to our
local machine "b". You COULD conceivably have a domain named "b.edu"
or "b.com", but even then "b.com!joe" would be clearly distinguishable
as non-local while "b!joe" is local. I can only get in trouble if one
of my local machine names matches one of the sites that I have a direct
uucp link to. For example I can't name a ucar.edu machine "b.ucar.edu"
if I also have a uucp link to a site whose uucp name is "b", or else
"b!joe" WOULD be ambiguous. Fortunately even a backbone site like us
has only a dozen or so uucp links, so that just means a dozen names
we can't use. Note that only DIRECTLY-CONNECTED uucp links have this problem,
not every name in the map. Not too hard for any halfway responsible site 
to avoid.

--Greg