A. You can use the "Dsmod user" command with the -disabled switch to enable a user account

dsmod user <user's distinguished name (DN)> -disabled no

or disable a user account

dsmod user <user's DN> -disabled yes

For example, to enable user John in domain it.uk.savilltech.com, I typed

dsmod user CN=John,CN=Users,DC=it,DC=uk,DC=savilltech,DC=com –disabled
   no

The system returned

dsmon succeeded:CN=John,CN=Users,DC=it,DC=uk,DC=savilltech,DC=com