Dnsmasq reservations - "fqdn will not work correctly"?

[Mpegger]

I'm in the process of switching from ISC to Dnsmasq and was reading through the OPNsense manual site again to make sure I'm sure configuring everything correctly when I came across this note under Dnsmasq DNS reservations:

A dynamic range like 192.168.1.100-192.168.1.199 and a reservation like 192.168.1.101 are valid and there will be no collisions.

The reservation can also be outside the dynamic range, but it is not recommended for simple setups as the dynamic dns registration with dhcp-fqdn will not work correctly.

If I understand this correctly, setting a reservation outside of the dynamic range will result in the FQDN of the reservation not working (not resolving)? Is this correct?

I've always setup those systems that require a fixed static IP (Proxmox for example) and static IP reservations via DHCP, seperate from the range that I used for dynamic assignments. I've always worked under the assumption since my early internet days, that setting a DHCP reservation in the dymanic range might result in collisions, for instance if the system that would normally recieve a fixed DHCP reservation wasn't on the network and a different system got assigned that particular IP address. I get that a modern setup like OPNsense should be "smart" enough to prevent that, but not having the FQDN resolve would be an issue. Can anyone confirm this? If its true and problems can occur, I'd have to redo how I have my IPs assigned on my LAN all over again.

[Monviech (Cedrik)]

Per default it sets the domain in the range exactly for the range.

That means reservations outside the range will get the default domain from general settings.

You can change that by opening advanced mode in the range and moving the domain type to interface.