MX record ordering

Kevin Darcy kcd at daimlerchrysler.com
Fri Mar 30 22:48:33 UTC 2001


As I said earlier, your mail partners must be violating RFC 974 if these are the
results you're seeing. The long-term solution is therefore to beat on them to
conform to the RFC.

A short-term solution would be to re-arrange the order of your MX records, e.g.
server1/server3/server2/server4.


- Kevin

lawrence.a.kravets at us.arthurandersen.com wrote:

> Okay with everyone's help I can see what's happening
>
> Here are the mx records
>
>  mailhosts      IN   MX   10   server1.zone.com.
>  mailhosts      IN   MX   10   server2.zone.com.
>  mailhosts      IN   MX   20   server3.zone.com.
>  mailhosts      IN   MX   30   server4.zone.com.
>
> When I cycle through in an isolated test environment here's what I see...  Doing
> an Nslookup looking for mx records...
>
> Test 1
>
> Server 1
> Server 2
> Server 3
> Server 4
>
> Test 2
>
> Server 2
> Server 3
> Server 4
> Server 1
>
> Test 3
>
> Server 3
> Server 4
> Server 1
> Server 2
>
> Test 4
>
> Server 4
> Server 1
> Server 2
> Server 3
>
> See a pattern?  Because of weighting and position on the list, Server 1 will get
> 75% of the responses as opposed to Server 2's 25% .  What should happen is that
> Server 1 and 2 should split 50/50.  But because of response list positioning  it
> does not.  In Bind 9 how can I fix this?  And rrset-order is not yet
> implemented.
>
> Thanks,
>
> Larry
>
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