[114754] in North American Network Operators' Group
Re: MX Record Theories
daemon@ATHENA.MIT.EDU (Valdis.Kletnieks@vt.edu)
Tue May 26 15:01:24 2009
To: nanog@nanog.org
In-Reply-To: Your message of "Tue, 26 May 2009 11:03:59 PDT."
<189373.71102.qm@web24704.mail.ird.yahoo.com>
From: Valdis.Kletnieks@vt.edu
Date: Tue, 26 May 2009 15:01:11 -0400
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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On Tue, 26 May 2009 11:03:59 PDT, gb10hkzo-nanog@yahoo.co.uk said:
> would be most interested to hear NANOG theories on the variety of MX
> record practices out there, namely, how come there seem to be so many
> ways employed to achieve the same goal ?
The trick here is that it isn't always *exactly* "the same goal". There's
multiple mail system architectures and design philosophies.
One often overlooked but very important design point for the *large* providers:
% dig aol.com mx
;; ANSWER SECTION:
aol.com. 2805 IN MX 15 mailin-01.mx.aol.com.
aol.com. 2805 IN MX 15 mailin-02.mx.aol.com.
...
;; WHEN: Tue May 26 14:40:41 2009
;; MSG SIZE rcvd: 507
That 507 is critically important if you want to receive e-mail from sites
with fascist firewalls that block EDNS0 and/or TCP/53. 5 bytes left. ;)
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