Failover for business continuity

[Mark Blackman]

On Wed, 30 May 2012, Ram wrote:
> So if not DNS based fail over , what is the other alternative.
> I cant move the IP , or re-announce BGP
> I cant have both servers in active-active mode

DNS failover is your best overall option for this case unless
you an exceptionally large budget to spend on this.

You would need to do some research on how many of your
end-user clients suffer from non-conforming DNS resolution
behaviours and just send them instructions on how to
manually refresh the DNS records when they complain they
can't reach the email server.

Depending on which failure modes you regard as most likely
or damaging, you could announce via DNS a proxy IP which
redirects to a working back-end. You would need to be confident
that proxy IP would provide higher availability than your
mail server though.

- Mark