You will have to examine how the question is worded. By default 11g will create all three tablespaces. You can however create a database with only SYSTEM and SYSAUX. Technically speaking you can upgrade pre-10g database and not add SYSAUX, or remove the SYSAUX tablespace after the database is created and therefore have a database with only a SYSTEM tablespace, but you would be ill advised to do so and I really don't think they would look for that in an answer.
From the 11.2 Administration Guide:
The SYSAUX tablespace is always created at database creation.
From another section of the Administration Guide:
An auto-extending undo tablespace named UNDOTBS1 is automatically
created when you create the database with Database Configuration
Assistant (DBCA)...
If no undo tablespace is available, then the
instance starts without an undo tablespace, and undo data is written
to the SYSTEM tablespace. You should avoid running in this mode.
From the 10.2 Concepts Guide:
...the SYSAUX tablespace is always created during database creation or
database upgrade...
During normal database operation, the Oracle database server does not
allow the SYSAUX tablespace to be dropped or renamed. Transportable
tablespaces for SYSAUX is not supported.
Note: If the SYSAUX tablespace is unavailable, such as due to a media
failure, then some database features might fail.
From the 10.1 SQL Reference:
You cannot drop the SYSTEM tablespace. You can drop the SYSAUX
tablespace only if you have the SYSDBA system privilege and you have
started the database in MIGRATE mode.
From the 10.1 Administrators Guide:
If the SYSAUX tablespace becomes unavailable, core database
functionality will remain operational. The database features that use
the SYSAUX tablespace could fail, or function with limited capability.
http://oradbpedia.com/wiki/The_SYSAUX_Tablespace has this take:
The SYSAUX tablespace is a new tablespace that is required in Oracle
Database 10g...
When you migrate to Oracle Database 10g, the SYSAUX tablespace needs
to be created as a part of that migration. This is done after mounting
the database under the new Oracle Database 10g database software. Once
you have mounted it, open the database in migrate mode with the
startup migrate command. After the database is open, you can create
the SYSAUX tablespace.
Note: The loss of the SYSAUX tablespace is not fatal to your database.
In our testing it appears that the only real impact is that certain
functionality related to the occupants of the SYSAUX tablespace is
lost.
Earlier versions did not have a SYSAUX tablespace:
SYSAUX is the name of the compulsory tablespace, introduced in Oracle
10g.
It depends on the GUI but they all should have a way of selecting the SYSDBA privilege. Toad has it appear as a drop-down box called 'Connect as:' as does Oracle Enterprise Manager. For SQL Developer you use the 'Role' box when creating a new connection.
As far as / as sysdba is concerned it just means that operating system authentication is being used so no password is needed. You can only use it if you are logged in as the oracle user or a member of the dba group (or for Windows, I believe as an administrator).
When you grant a user the SYSDBA privilege it only means they have the option to log in with the SYSDBA privilege and not that they will have dba privileges when they log in normally. The same is true for the SYS user: you can log in as SYS without the SYSDBA privilege and so lack the ability to shutdown the database, for example.
Best Answer
Why does a wait event that occurred 5 times accounts for 1.1% of your database wait time concern you as a potential threat? Is there some additional information that leads you to believe that this is a threat? Obviously, something has to be in your top 5 wait events. Is this event consistently one of the top wait events? Or did it just appear on one AWR?
The particular wait generally occurs when one session is trying to pin a cursor while another session is parsing it. Potentially, some of the 95% of the CPU related wait events could be the result of parsing (though you'd want to look at the number of hard parses elsewhere in the AWR). If you have an OLTP system, you should really only be doing any quantity of hard parses immediately after a reboot-- everything else should be using prepared statements and, at most, doing a soft parse. If you've got dynamic SQL somewhere in the system, removing that may help though it may also be a rather drastic step to save a few seconds.