Sort order of MX records while doing nslookup

[Jeff Reasoner]

On Mon, 2006-03-06 at 16:56, Martin Rådbo wrote:
> The "stupid" smtp-server is unfortunately impossible to change since it is 
> bundled with a fax gateway.
> 
> Of course the problem is gone if all or our mail servers is up and running 
> but the point with several servers is the failover function and to be sure 
> that our primary is our primary I would like the rrset function you talk 
> about.

It's a server option. Assuming it's supported in your version of bind,
you could use something like:

options {
	rrset-order {
		type MX name "*.domain.com" order fixed;
	};
};

This is not supported in all, or possibly most versions of bind 9, and
according to O'Reilly Bind 4th Ed., not supported prior to bind 8.2.
> 
> I think we do have the latest bind supporting this, do you have an example 
> of how to write the zone-fil?
> 
> Regards
> Martin Rådbo
> Teknologia
> 
> 
> "Jeff Reasoner" <jeff.reasoner at mail.hccanet.org> skrev i meddelandet 
> news:dui4i2$1ea0$1 at sf1.isc.org...
> : Unfortunately, probably not. My guess is that your mail server needs to
> : resolve MX records almost exclusively from servers you do not manage.
> : Answers to those queries, including the ordering, will be determined by
> : the authoritative servers not your client resolver. If that is not true,
> : and your servers are actually authoritative for all the domains your
> : mail server sends to, then a version of Bind that supports fixed rrset
> : ordering could do what you're asking.
> :
> : However, assuming that all the listed MXes are actually mail servers, it
> : shouldn't matter. I don't think there's any reason the mail has to go
> : *only* to the MX with the highest preference.
> :
> : Otherwise, "a very small and stupid smtp server" upgrade may be the only
> : fix.
> :
> : On Mon, 2006-03-06 at 11:39, Martin RÃ¥dbo wrote:
> : > If we run the command "dig domainname.com MX" or similar (could be 
> nslookup
> : > or whatever) the dns server responds with a list of MX-records for that
> : > particulary domain name, i.e.
> : >
> : > dig teknologia.com returns
> : > teknologia.com.         14400   IN      MX      20 mail3.latitud.net.
> : > teknologia.com.         14400   IN      MX      30 mail4.latitud.net.
> : > teknologia.com.         14400   IN      MX      10 mail.latitud.net.
> : >
> : > The sort order is different each time, is there a way to change this?
> : > I am aware that in normal circumstances this is without need because the
> : > mail server will automatically pick the row with the lowest weight 
> number.
> : >
> : > But we are in a situation running a very small and stupid smtp server (a
> : > part of a fax server program) and it seems to choose the first line on t 
> he
> : > list instead of the lowest weight numbered row.
> : >
> : > Is it possible to change the way BIND returns this list or not?
> : >
> : > Best regards
> : > Martin RÃ¥dbo
> : > Teknologia
> : >
> : >
> :
> : 
> 
>