When ReadOnly is set to 1, then no changes to the INI file will be made by the DHCP server. All newly recognized clients will get an IP address assigned but the respective client entry is not created. Which has the effect that the same IP address will be used next time for another client! This might be useful for test labs, that test one device after the other and explicitly want to assign the same IP address to each one.

ReadOnly=1        ; Default: 0

This feature was an added in V2.6.0.