OCP 1Z0 053 231

231.You upgraded Oracle Database 10g to Oracle Database 11g. How would this affect the existing 
users' passwords? 
A. All passwords automatically become case-sensitive. 
B. All passwords remain non-case-sensitive till they are changed. 
C. All passwords remain non-case-sensitive and cannot be changed. 
D. All passwords remain non-case-sensitive until their password attribute in the profile is altered. 
Answer: B 

http://docs.oracle.com/cd/E11882_01/server.112/e23633/afterup.htm#UPGRD12434

Reset Passwords to Enforce Case-Sensitivity

Starting with Oracle Database 11g Release 1 (11.1), you can enforce case sensitivity for passwords. For example, the passwordhPP5620qr fails if it is entered as hpp5620QR or hPp5620Qr. In previous releases, passwords were not case sensitive.

To take advantage of enforced case-sensitive passwords, you must reset the passwords of existing users during the database upgrade procedure. For new database instances, there are no additional tasks or management requirements. For upgraded databases, each user password must be reset with an ALTER USER statement.

Alternatively, you can change the default to make the password verifier case insensitive. For regular users, set the initialization parameter sec_case_sensitive_logon to false:

sql> alter system set sec_case_sensitive_logon=false;

For sysdba and sysoper users, you can generate a new orapw file using the new command line switch ignorecase.