I have OPNsense firewalls deployed to two different offices that communicate with each other via IPsec tunnels. The trouble is that I need to somehow keep the DNS records of 300+ hosts consistent between the two. It would be a hassle to change both firewalls every time there is a change in one location. Is there some way to sync DNS between two different firewalls in two different physical locations?
Are you using opnsense at both locations for dhcp and to register those dhcp leases to dns resolver?
Do both locations have separate domain names?
If so you can add a domain override on each router to allow the remote subnet to query their dns servers .
Example:
SITE A domain name is fries.local (192.168.2.1)
SITE B domain name is burger.local (192.168.3.1)
Site A pc needs to find a PC on Site B network by hostname. I can create dns record on site A or tell the router that any incoming query for domain burger.local send it to site B's dns server to resolve