From owner-freebsd-questions@FreeBSD.ORG Wed Nov 24 16:37:13 2004 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 886BD16A4CF for ; Wed, 24 Nov 2004 16:37:13 +0000 (GMT) Received: from helium.webpack.hosteurope.de (helium.webpack.hosteurope.de [217.115.142.90]) by mx1.FreeBSD.org (Postfix) with ESMTP id 0500343D5C for ; Wed, 24 Nov 2004 16:37:12 +0000 (GMT) (envelope-from me@hexren.net) Received: by helium.webpack.hosteurope.de running Exim 4.34 using asmtp helo=hexren.steenbuck.net) id 1CX08l-0000GS-Pz; Wed, 24 Nov 2004 17:37:12 +0100 Date: Wed, 24 Nov 2004 17:37:11 +0100 From: Hexren X-Mailer: The Bat! (v1.62i) Business X-Priority: 3 (Normal) Message-ID: <17020362449.20041124173711@hexren.net> To: freebsd-questions@freebsd.org In-Reply-To: <20041124141737.GA11648@dogma.freebsd-uk.eu.org> References: <20041123233501.GA82229@dogma.freebsd-uk.eu.org> <5557305861.20041124004849@hexren.net> <20041124000014.GA83249@dogma.freebsd-uk.eu.org> <8763344284.20041124022927@hexren.net> <20041124141737.GA11648@dogma.freebsd-uk.eu.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Subject: Re[2]: 4 part domain names X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: Hexren List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 24 Nov 2004 16:37:13 -0000 JM> : Every unique combination of subdomain.domain.tld could point to an JM> : arbitray other URL or IP. JM> : For example JM> : us.510.mail.example.com = example.com JM> : de.510.mail.example.com = europe.mail.example.com JM> I guess my question is this... JM> if 'us' is the name of the node (machine) and 'example.com' is the JM> registered domain name, what do the '510' and 'mail' parts uniquely JM> identify? Why not just 'us.example.com'? --------------------------------------------- Imagine not beeing a person with very simple needs like me or you but a big corporation. The corp where I work for example has adresses like uws015.ham.example.com and uws015.fra.example.com uws015 stands for "unix workstation number 15" ham stands for Hamburg and fra for Frankfurt (actually these are 3 letter airport codes as I'm employed by an airline) that makes sense as you now can delegate the numbering of workstations to the local sysadmins in Hamburg and Frankfurt. Whichout them having to worry about taking a number that is already used. For your question it is very likely that example.com is a big webmail provider it would therefore make sense for them to have many different login servers all over the world. I could guess that mail identifies a mail server (big surprise there) and us.mail.example.com would therefore be a mail server in the United States whereas de.mail.example.com would be a mail server in Germany. Why they use mail.example.com, because they maybe also have us.news.example.com used. So it makes sense to group their many servers by function first and then by location. 510 could identify a rack or a datacenter so that us.510.mail.example.com means "a mail server in the datecenter with the id 510 which serves the United States". But be aware that that extra meaning is arbitrary choosen by the Sysadmins at example.com they could aswell setup something like only.dump.persons.login.here.example.com and point their accountants to this server for login purposes. So if you are interested into why some specific specific subdomain names where choosen it would be wissest to ask the Sysadmins wo administer DNS for that domain. Hexren