The MaxLogonAttempts parameter restricts the number of successive logon attempts allowed to a user who submits an incorrect password.
If the number of erroneous logon attempts reaches the value specified in DBC.SysSecDefaults.MaxLogonAttempts, the system locks out the User ID from further logon attempts, for the duration of the password lockout time, as described in LockedUserExpire (Password Lockout Time). Further erroneous attempts during the password lockout time generate Event log entries that contain User Locked as the event type.