Explanation/Reference:
Explanation:
O12c is integrated in database don't have his own agent like in O11G then you cannot start up or shut down a database.

Explanation/Reference:
Explanation:
Interesting behavior in 12.1.0.1 DB of creating an undo tablespace in a PDB. With the new Multitenant architecture the undo tablespace resides at the CDB level and PDBs all share the same UNDO tablespace.
When the current container is a PDB, an attempt to create an undo tablespace fails without returning an error.

Explanation/Reference:
Explanation:
Backing Up a Whole CDB
Backing up a whole CDB is similar to backing up a non-CDB. When you back up a whole CDB, RMAN backs up the root, all the PDBs, and the archived redo logs. You can then recover either the whole CDB, the root only, or one or more PDBs from the CDB backup.
Note:
* You can back up and recover a whole CDB, the root only, or one or more PDBs.
* Backing Up Archived Redo Logs with RMAN
Archived redo logs are the key to successful media recovery. Back them up regularly. You can back up logs with BACKUP ARCHIVELOG, or back up logs while backing up datafiles and control files by specifying BACKUP ... PLUS ARCHIVELOG.

Explanation
A, Not D: In a CDB, PUBLIC is a common role. In a PDB, privileges granted locally to PUBLIC enable all local and common users to exercise these privileges in this PDB only.
C: A user can only perform common operations on a common role, for example, granting privileges commonly to the role, when the following criteria are met:
The user is a common user whose current container is root.
The user has the SET CONTAINER privilege granted commonly, which means that the privilege applies in all containers.
The user has privilege controlling the ability to perform the specified operation, and this privilege has been granted commonly Note:
* Every privilege and role granted to Oracle-supplied users and roles is granted commonly except for system privileges granted to PUBLIC, which are granted locally.

Note:
* Oracle Enterprise Manager Database Express (EM Express) is a web-based database management tool that is built inside the Oracle Database. It supports key performance management and basic database administration functions. From an architectural perspective, EM Express has no mid-tier or middleware components, ensuring that its overhead on the database server is negligible.
Incorrect:
Not B: For one database at a time.
Not C, Not E: Enterprise Manager Database Express features can be used against non-CDBs or
Oracle RAC database instances.
Not D: After the installation, your instance is started and your database is open. In the future, there
will be times, perhaps for doing database maintenance or because of a power or media failure,
that you shut down your database instance and later restart it.