If the DNS resolver is enabled, every DNS request from every interface will be processed by pfSense. Individual host records will be checked first, and if a match is found, the associated IP address is returned immediately.

By enabling the Register DHCP static mappings in the DNS Resolver option, you won’t have to worry about creating DNS records for these devices. This is advantageous, since as long as we create a static mapping for every device on our network, their hostnames will resolve automatically. Using this method, we will only have to add explicit hostname records for devices that specify their own IP addresses.