The alert log is a chronological log of messages and errors, and includes the following items:
* All internal errors (ORA-600), block corruption errors (ORA-1578), and deadlock errors (ORA-60) that occur
* Administrative operations, such as CREATE, ALTER, and DROP statements and STARTUP, SHUTDOWN, and ARCHIVELOG statements
* Messages and errors relating to the functions of shared server and dispatcher processes
* Errors occurring during the automatic refresh of a materialized view
* The values of all initialization parameters that had nondefault values at the time the database and instance start Note:
* The alert log file (also referred to as the ALERT.LOG) is a chronological log of messages and errors written out by an Oracle Database. Typical messages found in this file is: database startup, shutdown, log switches, space errors, etc. This file should constantly be monitored to detect unexpected messages and corruptions.

B: Data Pump can employ multiple worker processes, running in parallel, to increase job performance.
D: For export jobs, the master table records the location of database objects within a dump file set. / Export builds and maintains the master table for the duration of the job. At the end of an export
job, the content of the master table is written to a file in the dump file set.
/ For import jobs, the master table is loaded from the dump file set and is used to control the
sequence of operations for locating objects that need to be imported into the target database.

A: You can create and rebuild indexes online. Therefore, you can update base tables at the same time you are building or rebuilding indexes on that table. You can perform DML operations while the index build is taking place, but DDL operations are not allowed. Parallel execution is not supported when creating or rebuilding an index online.
B: Note:
* Transporting and Attaching Partitions for Data Warehousing Typical enterprise data warehouses contain one or more large fact tables. These fact tables can be partitioned by date, making the enterprise data warehouse a historical database. You can build indexes to speed up star queries. Oracle recommends that you build local indexes for such historically partitioned tables to avoid rebuilding global indexes every time you drop the oldest partition from the historical database.
D: Moving (Rebuilding) Index-Organized Tables Because index-organized tables are primarily stored in a B-tree index, you can encounter fragmentation as a consequence of incremental updates. However, you can use the ALTER TABLE...MOVE statement to rebuild the index and reduce this fragmentation.

A (not B,not E): The CREATE DATABASE ... ENABLE PLUGGABLE DATABASE SQL statement creates a new CDB. If you do not specify the ENABLE PLUGGABLE DATABASE clause, then the newly created database is a non-CDB and can never contain PDBs.
D: You can create a PDB by plugging in a Non-CDB as a PDB. The following graphic depicts the options for creating a PDB:

Description of cncpt358.png follows
Incorrect:
Not E:For the duration of its existence, a database is either a CDB or a non-CDB. You cannot transform a non-CDB into a CDB or vice versa. You must define a database as a CDB at creation, and then create PDBs within this CDB.

A - FALSE
Oracle-generated logs used to perform flashback database operations. The database can only write flashback logs to the fast recovery area. Flashback logs are written sequentially and are not archived. They cannot be backed up to disk.
B - FALSE
If the database control file is restored from backup or re-created, all accumulated flashback log information is discarded. You cannot use FLASHBACK DATABASE to return to a point in time before the restore or re-creation of a control file.
E - FALSE
Flashback Database can only undo changes to a data file made by Oracle Database.
It cannot be used to repair media failures, or to recover from accidental deletion of data files.
http://docs.oracle.com/database/121/BRADV/flashdb.htm#BRADV529
http://docs.oracle.com/database/121/BRADV/glossary.htm#BRADV90169