1. Configure pfSense as a DHCP server. See the Configuring the DHCP server recipe for details.
2. Create DHCP mappings for every device in the system that will obtain its IP address automatically through DHCP. See the Creating static DHCP mappings recipe for details.

3. Navigate to System | General Setup.

4. Ensure that no other DNS servers are specified.
5. Check the Allow DNS server list to be overridden by DHCP/PPP on WAN checkbox. This will enable pfSense to resolve external addresses using the DNS servers provided by your ISP through your WAN connection.
6. Click on the Save button.
7. Navigate to System | DNS Resolver.
8. Check the Enable DNS Resolver checkbox.

9. Check the Register DHCP static mappings in the DNS Resolver checkbox.

10. Create a Host record for any device that needs to be resolved but doesn’t have a DHCP mapping (that is, devices that define their own IP).
11. Create a Domain record for any DNS requests you’d like to redirect for a particular domain.
12. When you are done, click on the Save button.
13. Click on the Apply Changes button.