[nsd-users] reloading NSD zone configuration

Mohammad H. Al-Shami mshami at tagorg.com
Wed Apr 29 05:05:08 UTC 2009

Hi guys,

I've been interested in this issue for a while now, and I hope NSD has that soon. But for the time being I propose a workaround.

I'm not a big fan of zone transfers, hated them since the day I set up my first DNS server. Currently I use a patched version of VegaDNS with a backend Perl script to manage my zones. The Perl script generates the configration and zone files then copies them to all my servers.

As for adding/removing a zone, at the end of the Perl script:
1) Shut down server A
2) Wait 5 seconds
3) Start server A
4) Wait 5 seconds
5) Shut down server B

With this you have only one of your servers restarting at a certain moment.

When I wrote the script just restarting NSD caused it to generate an error, if I remember correctly it couldn't bind to port 53. This happened only the first time NSD was restarted after a server reboot, which was weird. Since the script worked properly as it is I haven't bothered in checking it again.

Hope that helps.

Mohammad H. Al-Shami

On Tuesday 28 April 2009 12:36:29 Antti Ristimäki wrote:
> On Tue, 28 Apr 2009, Jelte Jansen wrote:
> > If you restart NSD, with some new slave zones added, it will serve existing
> > zones as soon as it is up (i.e. within seconds on most systems, see below for my
> > private setup and some very anecdotal timing benchmarks). It will also start to
> > transfer the new slave zones, but while it is doing that it already serves
> > existing ones.
> Thank you for this very valuable information. Restart times of this 
> magnitude would be acceptable for us, given that the frequency of zone 
> additions is rather low in our environment.
> > Throwing queries against it
> > from the other side i would estimate that 1 or 2 seconds of those are spent
> > waiting for the previous process to stop, at which point it is still serving.
> Regarding the process stopping phase, what would be expected to happen in 
> case that one or more zone transfers are pending at the same time when 
> SIGTERM is sent to the previous process?
> BR,
> Antti
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