To make changes in an active directory a writable domain controller.
Read Only domain controllers(RODC):- It is basically a server it responds to requests of security authentication and It hosts an active directory database's read-only partitions.
This is not the case with writable domain controller since it can make changes to the Active directory.
Considering the fact that only numbers are permitted (0 - 9) which gives 10 characters and also that the digits can be repeated, the total number of possible PINs that are possible is 10 x 10 x 10 x 10 = 10000
