@pfkomrad said in Can you implement DNS Round Robin for local IP's?:
Ideally though, this should be hidden from the client
For what possible reason? If you have 2 piholes that resolve the same stuff, then hand them both out to your clients. Any client is going to be smart enough to move to the other listed ns if the first one does not answer.
If you want your piholes to resolve your dhcp clients names - then forward them to pfsense that is acting as your dhcp server.
So clients ask pihole, if asking for www.domain.com and not blacklisted, it forwards to pfsense that resolves it or forwards (however you like it to work - resolving is default pfsense setup). If its a local domain, then pfsense would respond and pi-hole would hand it back to client.
Seems like your overthinking something that is quite simple. I also don't get the need for registration of dhcp in a home setup to be honest. If there is something you want to be able to resolve - why not just make sure its always on the same IP either with static and host override or dhcp reservation and let pfsense register the registration.
Clients can list as many ns as you want.. The only thing you need to be sure of is any and all of the listed ns for the client need to resolve the same stuff. You can point client to say pihole and google and then wonder why sometimes fqdn is blocked and sometimes its resolved. You can never be sure what ns a client will query when you list more than 1, doesn't matter what order you hand them to the client. ALL ns listed on a client need to be able to resolve the same stuff, or block the same stuff, etc. Pointing a client to 1 ns that can resolve local, and another that can not is asking for failure.