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

Gavin Brown gavin.brown at centralnic.com
Tue Oct 9 11:57:13 CEST 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:

http://bert-hubert.blogspot.co.uk/2012/10/on-binding-datagram-udp-sockets-to-any.html

On 16/08/2012 15:39, Gavin Brown wrote:
> Hi there,
>
> I have a FreeBSD box (hostA) running NSD. It has a management address
> (10.0.0.2) and a service address (10.0.0.3). It is part of a clustered
> pair with a Linux machine (hostB) that has a management address
> (10.0.0.4) and a service address (10.0.0.5). 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 (10.0.0.5) 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 (10.0.0.2) since that is the
> "primary" interface of the host. I can fix this during normal operations
> by adding an ip-address entry for 10.0.0.3.
>
> However, during failover, queries sent to 10.0.0.5 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
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