pfSense

Forum: https://forum.pfsense.org/index.php?topic=89043.0
Add a "Static Mapped" DHCP entry for some MAC address but do not specify an IP address. This can be useful when you want to provide some special DHCP parameters to a client but are happy for it to get an IP address from the pool.
Connect the client. It has a dynamic IP from the pool.
Status->DHCP Leases - the client MAC is shown in 2 rows of the table - one row as the dynamic data, one row as the "static" entry without an IP address.
1) The dynamic data has the "+" button displayed at the end - that is not appropriate because there is already a static entry. The edit button that is on the end of the static row is the appropriate one.
2) Could not display the dynamic row, and put the current dynamic IP from the pool into the IP address box on the static row. That would keep the information available and remove confusion from having 2 rows. Need to think what to do about the Lease Type column - the 2 rows have "active" and "static" in them. In a sense this entry is both at once.

Some useful screenshots are on that forum post.