On Sun, 12 Jul 1998, Ben Smithurst wrote:
> > Not so: MX only works for other MTAs attempting to send e-mail by looking
> > up MX. It does nothing for Joe ISP user who has 'smtp.isp.com' set up as
> > his outbound host.
>
> No, but if smtp.isp.com has multiple IP addresses, Joe will get a
> randon one of however many there are. Or that's how I understand it
> to work, and it's how many ISPs do it (Demon certainly do).
Yes, but if the DNS looks like this:
mail.isp.com. IN A 10.1.1.1
IN A 10.1.1.2
And the machine at 10.1.1.2 goes down, then 50% of the Joe users out there
will get the IP of a dead machine until DNS is changed or 10.1.1.2 comes
back up. The load balancer provides a "virtual" IP that can be directed
at either or both of the machines behind it based upon that machine's
ability to serve mail (be that determined by ping or more sophisticated
methods).
--
j.
James FitzGibbon james@???
System Engineer, ACC Global Net Voice/Fax (416)207-7171/7610
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