|
On Mon, 14 May 2001, Michael E Brown wrote:
>
>
> On Mon, 14 May 2001, Joseph Mack wrote:
>
> > Michael E Brown wrote:
> >
> > > > As far as I am aware DNS should respond with all MX records for a
> > > > request. The MTA should then choose one at random from the same
> > > > piority.
> >
> > > The above statement is correct.
> >
> > And if the machine for that MX record happens to be down, the MTA
> > will pick another MX record and try to deliver it there? (This has
> > to be true, I'm sure I read this in the Bat book).
>
> Yes. (As long as there _are_ multiple MX records :-)
>
I think that central load balancing is more efficient in resource
utilization than randomly picking up servers by clients, basic queuing
theory can prove this. For example, if there are two mail servers grouped
by multiple DNS MX records, it is quite possible that a mail server of
load near to 1 still receiving new connections (QoS is bad here), in the
mean while the other mail server just has load 0.1. If the central load
balancing can keep the load of two server around 0.7 respectively, the
resource utilization and QoS is better than that of the above case. :)
Regards,
Wensong
|
