MX records

[Barry Margolin]

In article <8gg3td$od9$1 at porthos.nl.uu.net>,
systemec <mteelen at systemec.nl> wrote:
>Hello,
>
>We use several mailservers which are specified in the DNS records naturally,
>for example:
>      MX   10    smtp1.systemec.nl.
>      MX   20    fallback.nl.uu.net.
>
>Since we use more mailservers there are more MX records:
>    MX   10    smtp2.systemec.nl.
>
>    MX   10    smtp3.systemec.nl.
>
>etc.etc.
>
>We always use the same server for MX 20 (fallback.nl.uu.net.)
>I assume then it is not necessary to specify each MX 20 record for the
>various mailservers?
>
>And if the above statement is true, what if I want to specify different MX20
>records for the various mailservers ?
>
>In other words, in what way is the DNS record being  processed to find the
>necessary MX records.

Backup mail servers are associated with the name that the MX record is
attached to, not the servers that are listed.  I.e. when you have

foo.com.  MX 10 server1a
          MX 10 server1b
          MX 20 server2a
          MX 20 server2b

it affects mail addressed to user at foo.com.  The sender will first try to
send to each of the MX10 hosts in a random order, and then try to send to
each of the MX20 hosts in a random order.

-- 
Barry Margolin, barmar at genuity.net
Genuity, Burlington, MA
*** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.
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