Round-Robin for mail/smtp hosts

[Kevin Darcy]

Matt Prigge wrote:

> > When you say "checking" mail, though, this implies remote access to a
> mailbox,
> > via POP or IMAP or whatever. In DNS terms, this doesn't matter, but in
> mail
> > terms you of course need to make sure that those mailboxes are shared
> properly
> > on the various server(s) included in that round-robin name, and can handle
> > potential conflicts, e.g. being updated in incompatible ways on two
> different
> > nodes simultaneously.
>
> Right. The two machines that would be set up this way are POP/IMAP proxies
> which dynamically redirect traffic to a distributed set of backend servers,
> so this isnt a problem in this case.
>
> What I am most curious about is how the clients (OE/Netscape/etc) implement
> failover using multi-A RRsets. Is it handled by the underlying OS? Or is it
> the client really responsible for trying the first RR and then, if that
> fails, trying subsequent RRs out of the same set? Do some clients not do
> this?  This scheme seems like it will work well as a low-grade form of load
> balancing, but how well will it work as far as redundancy is concerned?

The client is responsible for the failover. YMMV.


- Kevin