Explain an ORA-01555

Explain an ORA-01555 ?

You get this error when you get a snapshot too old within rollback. It can usually be solved by increasing the undo retention or increasing the size of rollbacks. You should also look at the logic involved in the application getting the error message.

Explain the difference between $ORACLE_HOME and $ORACLE_BASE. 
ORACLE_BASE is the root directory for oracle. ORACLE_HOME located beneath ORACLE_BASE is where the oracle products reside.

How would you determine the time zone under which a database was operating? 
select DBTIMEZONE from dual;

Explain the use of setting GLOBAL_NAMES equal to TRUE. 
Setting GLOBAL_NAMES dictates how you might connect to a database. This variable is either TRUE or FALSE and if it is set to TRUE it enforces database links to have the same name as the remote database to which they are linking.

What command would you use to encrypt a PL/SQL application? 
WRAP