Mail Server (DNS) Migration

[Kevin Darcy]

Jack Spratt wrote:

> Hello,
>
> I am in the process of moving an existing mail server from its current
> location to a new one. I have a peer relationship between the servers
> that allows the two servers to distribute email messages sent to the
> same domain, to their correct Mailboxes and user accounts. I've
> accomplished this within the mail server package (IMail) and by
> creating dual MX records for the offending domain like so:
>
> ---
>
> mail1 IN A     192.168.0.5
> mail2 IN A     192.168.0.6
>
> @ IN MX    10 mail1.domain.com.
> @ IN MX    10 mail2.domain.com.
>
> mail IN CNAME mail1
>
> ---
>
> Pay no attention to the priority level, it is a requirement of my
> comfiguration. What this gives me is a level of fault tolerance. The
> issue I have is when my users check their email at "mail.domain.com",
> is there any way I can create the same level of fault tolerance against
> the "mail" CNAME record so that it will hit either "mail1" or "mail2"
> depending on which one is available at the time of the check. I want to
> avoid the potential 24 hour wait for propogation and need this to work
> seamlessly. Does anyone know how I could accomplish this?

You could try replacing that CNAME with 2 A records, one for each address.
If the clients are smart enough, they'll fail over automatically after a
short delay. This delay may even be configurable.


-Kevin