[nsd-users] Question about response source address and dynamic interfaces

Gavin Brown gavin.brown at centralnic.com
Tue Oct 9 09:57:13 UTC 2012

I was never able to resolve this issue, but Bert Hubert recently posted 
on a related topic. If NSD did what PowerDNS now does, this would 
resolve my problem!

On binding datagram (UDP) sockets to the ANY addresses:


On 16/08/2012 15:39, Gavin Brown wrote:
> Hi there,
> I have a FreeBSD box (hostA) running NSD. It has a management address
> ( and a service address ( It is part of a clustered
> pair with a Linux machine (hostB) that has a management address
> ( and a service address ( DNS queries are sent to the
> two service addresses. Heartbeat is used to co-ordinate the pairs: if
> hostB goes offline, then the service address ( is brought up on
> hostA so that it can answer queries, and vice versa.
> The problem is this: without an ip-address entry in nsd.conf, responses
> are sent from the management address ( since that is the
> "primary" interface of the host. I can fix this during normal operations
> by adding an ip-address entry for
> However, during failover, queries sent to will be answered with
> the wrong source address. Again, I could fix this using an ip-address entry.
> But - when the machine boots, this IP address isn't assigned to hostA,
> so if it appears in nsd.conf, NSD will refuse to start. BIND (which I'm
> using on hostB) doesn't have this problem.
> Has anyone else solved this problem? Or do I need to write scripts to
> munge nsd.conf and restart it during failover/failback?
> Thanks,

Gavin Brown
Chief Technology Officer
CentralNic Ltd
Innovative, Reliable and Flexible Registry Services
for ccTLD, gTLD and private domain name registries

CentralNic Ltd is a company registered in England and Wales with company
number 4985780. Registered Offices: 35-39 Moorgate, London, EC2R 6AR.

More information about the nsd-users mailing list