Re: How do you keep dhcpd and nsd/unbound in sync?

> On Thu, Feb 26, 2026 at 09:37:03AM +0000, Martin wrote:
> > Currently we run Unbound without NSD for our local net where
> > Unbound has a local file with IPs and PTRs for the LAN. We
> > also use dhcpd to assign fixed IPs based on the MAC.
> >
> > So far all is done manually. Is there some way to automatically
> > add hosts and hostnames to Unbound when a lease is granted from
> > dhcpd or some other way?
> >
> > Kind regards
> >
>
> I do it the other way round: use nsd (behind unbound, but that's not
> relevant here) to match IPs and hostnames, and then use hostnames
> instead of IPs in dhcpd.conf. E.g.
>
>
> zone file:
>
> foo.example.com 192.168.77.2
>
>
> dhcpd.conf:
>
> host foo {
> hardware ethernet aa:bb:cc:dd:ee:ff;
> fixed-address foo.example.com;
> }
>
> Changes to the zone file require restarting dhcpd, so that they
> propagate.
>
> Big caveat: dhcpd start becomes dependent on DNS, obviously. If DNS
> fails to start, or isn't responding for some reason (especially relevant
> if it is running on a different machine), dhcpd will fail to start, and
> things might get messy. The trade-off between sturdiness and DNS/DHCP
> maintenance overhead works for me, but might not work for others.

This works really well, thanks!