MX and CNAMES revisited, listservs

Re: MX and CNAMES revisited, listservs

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At 11:55 PM -0500 4/18/00, billc@greenbuilder.com wrote:
>Hi folks,
>
>A month or so ago I learned that MX records shouldn't be CNAMEd. So I went
>through and changed all my records.
>
>Now I'm wondering about my listservs.
>
>Part of the reason I'm wondering about it is that I want to set up a
>secondary mailserver to hold mail in the event my listserv machine goes
>down, and deliver it once it comes back up. I have a similar setup for my
>mailserver, and would like to use the same mailserver as the secondary list
>machine. If the relevant part of my setup is:
>
>greenbuilder.com. MX 10 mail.greenbuilder.com.
>greenbuilder.com. MX 20 mail2.greenbuilder.com.
>mail.greenbuilder.com. A 216.171.28.121
>mail2.greenbuilder.com. A 216.171.28.3
>lists.greenbuilder.com. A 216.171.28.120
>
>where mail2 is the backup for mail1, can the listserv just get a second
>line that says:
>
>lists.greenbuilder.com. A 216.171.28.3
>
>with the appropriate settings in the mail2 server to hold and send? Should
>lists.greenbuilder.com be treated as an MX, since it is essentially a mail
>server? What about the CNAMES that point to lists.greenbuilder.com - they
>appear to be working just fine, but then again I had not seen any problems
>with the CNAMEd MX records either...
>
>I once thought I knew what I was doing. Now I'm not so sure. ;-/

You should not add the second A record for lists.greenbuilder.com.
You should instead add the following MX records:

lists.greenbuilder.com. MX 10 lists.greenbuilder.com.
lists.greenbuilder.com. MX 20 mail2.greenbuilder.com.

CNAME records that resolve to lists.greenbuilder.com will not cause
any problem and should work fine, so long as they don't appear in an
MX record. If you want to add MX records for lists.otherdomain.com,
have those MX records resolve to lists.greenbuilder.com and
mail2.greenbuilder.com.
____________________________________________________________________
Chris Buxton cbuxton@menandmice.com
Men & Mice http://www.menandmice.com
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