Mailing List Message #15437
From: Bill Cole <>
Subject: Re: SIMS dual domains
Date: Wed, 7 Feb 2007 23:51:36 -0500
To: SIMS Discussions <>
At 4:22 PM -0600 2/7/07, billc  imposed structure on a stream of electrons, yielding:
At 9:45 AM -0800 2/7/07, Christopher Bort wrote:

 Set up CNAME on old domain name record: CNAME
 Remove A record for
 MX record on old domain points to

That's all optional and entirely up to you. The record for can remain as an A, especially if you're reasonably
confident that your server will keep the same IP address for a while.
CNAMEs can get messy, so I usually try to avoid them when an A record will
do the job.

Actually, there are those that consider it mandatory that MXs point to A records.

Yeah, like anyone has read the relevant RFC's. Or the code for a DNS resolver.

 QDNS won't even let you put in a C name for an MX these days. (sorry, i'm not one of those RFC quotin' kind of guys, but that's probably where it stems from)

Relevant RFC's: 974, 1035, 1912, 2181

Bottom line: it has been explicitly wrong to point an MX at a name that has a CNAME for every one of the past 20 years, the entire history of the MX record type. People still do it, but they really need to have their mail broken frequently and mysteriously...

Bill Cole                        

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