MX record Question
Mark.Andrews at nominum.com
Mark.Andrews at nominum.com
Thu Aug 9 21:51:38 UTC 2001
> > The question is how does this work?
> >
> > MX 10 mail01.domain.com
> > MX 10 mail02.domain.com
> >
> >
> > If for example this in theory will round robin, what would happen if
> > mail01
> > were to go down, would mail02 be the next on the list even after being
> > resolved? My email admin wanted to know how this would work. We think
> > that
> > it should go to the next one in line, this of course depending on the MTA.
> > Could someone shed some light.
> >
> > Thanks,
> >
> > Mark
> >
> >
> When BIND returns a response to an MX query for this domain name, it will
> return the two entries ordered in round-robin fashion. So if mail01 was
> listed before mail02 in the response, the remote mailserver would first
> attempt to contact mail01, and then after a minute the TCP connection to
> port 25 (SMTP server) would fail, so the remote server would then try mail02
> and the mail would go through.
>
> Steve
It shouldn't matter about the order of the returned records as
the MTA is require to randomise the order it selects from equal
preference MX targets.
Mark
--
Mark Andrews, Nominum Inc.
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: Mark.Andrews at nominum.com
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