replicating dynamicly updated servers..

Kevin Darcy kcd at
Tue Sep 5 21:16:41 UTC 2006

Gregory Machin wrote:
> Hi
> I have a master dns server (bind 9) that has 2 zones that clients update
> dynamicly... Bind doesn't allow for slave serve to be updated for a dynamic
> zone ....
> How can I work around this .. as I need a backup server so if the primay
> master is down the clients can still resolve ...
What you're describing -- having multiple servers that can accept 
Dynamic Updates for the same zone -- is usually called "multi-master" 
and vanilla BIND does not support it at this time. The problem, as I 
understand it, is what to do about conflicting updates, e.g. client A 
adds record X but client B deletes X. Do you go by timestamp, or some 
other attribute of the respective updates? The only way I'm aware of 
that multi-master has been implemented with at least partial success is 
when there is a back-end database -- e.g. LDAP for Active 
Directory/Microsoft DNS, or a regular DBMS such as Oracle or Sybase for 
Lucent's QIP product (using a modified version of BIND) -- which acts as 
a kind of "central arbitrator" and will prevent conflicting updates from 
getting out of hand.

                              - Kevin

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