At 01:56 PM 1/26/00 WayneB6094@xxxxxxx wrote:
> Presuming a domain name of <www.domain.com>, I create an A record for > <mail.domain.com> (with the main IP# for the box on which I'm receiving > email), and an MX record pointing <domain.com> to <mail.domain.com> with a > precdence of 10. > > That gives me modularity and scalability. > Those are nice buzzwords, but what functionality does it provide, that you couldn't get another way?
You can do it any way you want; I never said you couldn't. I explained what I did, and why. I really forget that most of the people on this list neither are experienced systems administrators nor want to learn to be. For that I apologize.
(And lest you think the above to be meant in some way demeaning, it isn't. For example, I am neither an auto mechanic, nor do I want to be, but I want my car to run when I need it.)
Okay: I create an A record pointing to <mail.domain.com> because that creates a virtual machine called <mail.domain.com>. I can point it to any IP# I want. I point it to the main IP# for the box on which I receive email because the main IP# is least likely to ever be deleted, changed, or pointed to another machine, therefore it's most likely to give me a supportable environment forever.
I create an MX record pointing to that A record because some MTAs (Mail Transport Agents) won't send mail to mail-servers defined in CNAME records or PTR records.
And the reason I define a virtual machine to begin with is so that as I grow larger or smaller I can point this virtual machine (by changing the IP# in its A record) to any other virtual or real machine. One point of change. That equals modularity and scalability.
Being in the DNS hosting business (ns-one.net) and the email-business (emailwholesale.com) I'm often called in to "fix" dns records so mail will work properly for complex domains. Some of the stuff out there is very hard to follow, very hard to understand. The steps I've defined above leave an easy-to-understand "audit" trail, if you will, that you can follow and readily change as your growth dictates.
Jeff -- Jeff Lasman, nobaloney.net <jblists@xxxxxxxxxxxxx> <www.nobaloney.net>, <www.mailtraqna.com>, <www.email-lists.com>