Warning: If you are prepopulating the passwords of user accounts, be sure to prepopulate the passwords of computer accounts ...

Warning: If you are prepopulating the passwords of user accounts, be sure to prepopulate the passwords of computer accounts that these users will be using as well.  In order for a user to be able to log on to a read-only domain controller (RODC) when no writable domain controller is available, the passwords for both the user account and the computer account of the computer that the user is logging on to must already be stored on the RODC. Prepopulating the password for a user account will succeed only if the account is included in the Allowed list of passwords that can be cached on the RODC.