Moving dynamic zones to new master+slave pair without interruptions

Tony Finch dot at
Thu Jan 7 10:32:31 UTC 2016

Peter Rathlev <peter at> wrote:
> On Wed, 2016-01-06 at 16:05 +0000, Tony Finch wrote:
> > * Set up a new hidden master, with copies of your zones. (See below)
> >
> > * Change your existing servers to slave from the new hidden master
> > instead of the old master. Reconfigure the old master to be a slave
> > of the new one.
> Wouldn't this ruin dynamic updates from the DHCP servers? These updates
> need to be sent to the master.

The master name in the zone's SOA record should point to the real master,
i.e. the "hidden" master in your new setup. Updates are normally sent to
the SOA master.

> This made my think... Maybe I could just AXFR from the running slave
> and use the output as zone files on the master. As far as I can see
> this should Just Work™.

Yes, though you should also ensure there isn't any stray journal file on
the new master. (This is essentially what nsdiff does, but it uses
nsupdate to write the zone data to the master instead of just dumping to a

f.anthony.n.finch  <dot at>
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