Will MX lookup ignore MX on server which also has NS delegation.

Chris Buxton cbuxton at menandmice.com
Thu May 29 19:19:35 UTC 2008

On May 29, 2008, at 9:05 AM, Greg Chavez wrote:
> On Thu, May 29, 2008 at 11:52 AM, Robin Farrell <robinfarrell at gmail.com 
> > wrote:
>> We have a client that is using NS to delegate their DNS to us and  
>> we will
>> host their MX records.
>> They are refusing to remove legacy MX and A records for the domain in
>> question from their DNS, yet they have the correct NS records in  
>> place for
>> the domain in question to be redirected to us.
>> Could this possibly effect how dns MX/A lookups are redirected to our
>> servers?
> They're *refusing*?  Well, that's peculiar behavior.  But it shouldn't
> matter.  You can't partially delegate a domain to another authority.
> It's all or nothing.  What happens when you query their server for the
> NS records of the delegated domain?  I submit that the delegation is
> not in place as you describe.

More to the point, what happens when you query the parent zone's name  

I've been seeing several people lately, people who should know better,  
telling me they can create a sideways delegation, a re-delegation of a  
zone from the servers listed in the parent's delegation NS records to  
another set of servers, without updating the delegation NS records. It  
sounds like this is what the OP's client is doing.

Chris Buxton
Professional Services
Men & Mice

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