MX and CNAMES revisited, listservs

Re: MX and CNAMES revisited, listservs

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>>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.

Let me correct one detail of what I said earlier:

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 ** nor have the same name as an MX record **.

So given MX records for lists.domain.com, you shouldn't also have a
CNAME record named lists.domain.com.

>Ok, so is the following kosher?
>
>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. MX 10 lists.greenbuilder.com.
>lists.greenbuilder.com. MX 20 mail2.greenbuilder.com.
>lists.greenbuilder.com. A 216.171.28.120

Yep, that looks fine.

>and then on client's domain records, have:
>
>domain.com. MX 10 mail.domain.com.
>domain.com. MX 20 mail2.domain.com.
>mail.domain.com. A 216.171.28.121
>mail2.domain.com. A 216.171.28.3
>lists.domain.com. MX 10 lists.greenbuilder.com.
>lists.domain.com. MX 20 mail2.greenbuilder.com.

The above is not a good idea, as explained below.

>Can/should that instead be:
>
>domain.com. MX 10 mail.greenbuilder.com.
>domain.com. MX 20 mail2.greenbuilder.com.
>lists.domain.com. MX 10 lists.greenbuilder.com.
>lists.domain.com. MX 20 mail2.greenbuilder.com.
>
>so that in the event that I move the mail servers to different IPs, I
>don't have to change A records for every domain?

Absolutely right. It's a very good idea to only ever refer to a given
mail server by one name, in all of your MX records that point to it.
It's also a generally good idea to have the PTR record for that
address refer to that same name.

Not only does this mean that you only ever have to change one or two
records if you move your mail server, it also means that you're less
likely to run afoul of anti-spam measures.
____________________________________________________________________
Chris Buxton cbuxton@menandmice.com
Men & Mice http://www.menandmice.com
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