Which two statements are true about the Automatic Diagnostic Repository (ADR)? (Choose
two.)
A.
The ADR base keeps all diagnostic information in binary format
B.
SQL*Plus provides the ADRI script, which can be used to work with ADR
C.
The ADR can be used for problem diagnosis only when the database is open
D.
The ADR can be disabled by settting the DIAGNOSTIC_DEST parameter to null
E.
The ADR can be used for problem diagnosis even when the database instance is down
F.
The ADR base is shared across multiple instances
E and F are correct:
https://docs.oracle.com/cd/B28359_01/server.111/b28310/diag001.htm
For E: The Automatic Diagnostic Repository (ADR) is a directory structure that is stored outside of the database. It is therefore available for problem diagnosis when the database is down.
For F: It has a unified directory structure across multiple instances and multiple products.
For all the other wrong answers:
https://docs.oracle.com/cd/B28359_01/server.111/b28310/diag001.htm
For A: Core Files
A core file contains a memory dump, in an all-binary, port-specific format. Core file names include the string “core” and the operating system process ID. Core files are useful to Oracle Support engineers only. Core files are not found on all platforms.
For B: http://docs.oracle.com/cd/B28359_01/server.111/b28319/adrci.htm
ADRCI has a rich command set, and can be used in interactive mode or within scripts. In addition, ADRCI can execute scripts of ADRCI commands IN THE SAME WAY that SQL*Plus executes scripts of SQL and PL/SQL commands. [It does not come from SQL*Plus]
For C: see E
For D: The ADR root directory is known as ADR base. Its location is set by the DIAGNOSTIC_DEST initialization parameter. If this parameter is omitted or left null, the database sets DIAGNOSTIC_DEST upon startup as follows:
If environment variable ORACLE_BASE is set, DIAGNOSTIC_DEST is set to the directory designated by ORACLE_BASE.
If environment variable ORACLE_BASE is not set, DIAGNOSTIC_DEST is set to ORACLE_HOME/log.