On Tue, 26 May 2009 11:03:59 PDT, gb10hkzo-na...@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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