bind selective delegation, is it possible?

Mark Andrews Mark_Andrews at
Wed Mar 28 00:09:35 UTC 2007

> Hi,
> I am trying to solve a DNS problem.   I am trying to delegate my
> to another nameserver for the A record  but I still want
> the MX record to be served by the original server.  The reason for
> this is that I have load balancers and they expect to be delegated the
> NS authority for the domain of the website (so I have delegated
> with no problem)  Now the problem I am having is that I
> also want to be able to load balance  since it is
> quite common not to use the wwws nowadays.  The nameserver
> functionality on these loadbalancers is primitive and they only
> support A records.  If I put in an NS record on the master dns server
> and delegate to my load balancers, my email breaks because
> the DNS engines on the load balancers dont serve up MX records, only A
> records, but the delegation is relinquishing authority from the master
> server.  If I use a CNAME, its the same thing, it delegates the entire
> domain and the master server becomes no longer authoritative for the
> MX record.  Is there a way I can delegate to my load
> balancer for A records only but retain authority for the MX records?
> Or is there some other better way to accomplish this?
> Thank you very much.
> Zach

	That is not possible in the DNS.  In the DNS you delegate
	the entire namespace.

	Some load balancers can let querys fall through to another
	name server.  Note you have to take care to set such systems
	up correctly.


Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at

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