KEA DHCPv6 DNS registration

[IonutIT]

I really don't understand why this is happening but for ONE (any only one) of my DHCPv6 static reservation there's no DNS registration. All other reservations have proper functioning DNS registrations in Unbound.

Here is what my DHCP static mappings settings look for one of my VLANS:

And here is what host lookup looks like for these 3 hosts:

As you can see the last entry for unifi does not register with DNS and I can't for the life of me understand why. I've deleted the reservation, made it again, change the reserved IP address, restarted Unbound, restarted KEA, rebooted pfSense, nothing worked.

In trying to figure out what the hell is happening, I noticed a weird entry in my NDP Table:

And lo and behold that host does resolve to my static DHCPv6 allocation:

Does someone has any idea why this particular reservation resolves in DNS with a different domain name? What's going on?

[Gertjan]

@IonutIT

Copy 'unknown' into the search tool, in the forum part, DHCP and DNS and you'll find other stories about this 'unknown'.

edit : here : pfSense 2.8.1: Kea DHCPv6 IPv6 Static Lease Allocation Fails (ALLOC_ENGINE_V6_ALLOC_FAIL_SUBNET) for Known Client, Inconsistent DNS

Also, I found this yesterday : PHP Fatal error: Allowed memory size exhausted in /usr/local/bin/kea2unbound

I'm using that new /usr/local/bin/kea2unbound since yesterday. So far, very good.

[IonutIT]

@Gertjan

Thanks for pointing those out. I also posted on that thread there with some updates.

[IonutIT]

Wow... ok figured it out. The links provided in @Gertjan post put me on the right path. It seemed strange that only Ubuntu Server hosts were affected so I started digging on that.

Turns out that by default in Ubuntu Server systemd-resolved is not configured to use the domains passed by DHCP (either v4 or v6) not by RDNSS.

So all I had to do was to edit /etc/systemd/networks/networkd.conf to have UseDomain=true and just like that, by magic the hostname is properly registered in Unbound...