The Data Guard Monitor (DMON) process is a key component of Oracle Data Guard. It plays a crucial role in managing and monitoring the state of both the primary and standby databases in a Data Guard configuration.
* Performing role transitions when switchover requests are made (A): DMON is responsible for coordinating the switchover process between the primary and standby databases. This involves safely transitioning the roles of the databases to ensure data protection and availability.
* Maintaining information about all members of the broker configuration in binary configuration files (B): DMON maintains detailed information about the databases in the Data Guard configuration, including their roles, states, and network addresses. This information is stored in binary configuration files, which are used by the Data Guard Broker to manage the Data Guard environment.
* Activating role-based services appropriately in the various database instances of the configuration, based on the database role (C): DMON activates services that are appropriate for the role of each database in the Data Guard configuration. For example, it may activate different services on a primary database than on a standby database, based on the specific requirements of each role.
References:
* Oracle Data Guard Concepts and Administration
* Oracle Data Guard Broker documentation

The DBMS_ROLLING package facilitates a rolling upgrade process across a Data Guard configuration. The START PLAN procedure in particular handles several critical actions, including:
Creating a guaranteed restore point on the standby databases (B): This ensures that the standby databases can be reverted to their state before the rolling upgrade process in case of any issues.
Building a LogMiner dictionary on the primary database instance (C): This is necessary for logical standby databases to interpret redo data during the SQL Apply process.
Creating a guaranteed restore point on the primary database (D): Similar to the standby databases, this ensures that the primary database can be reverted to a known good state if necessary.
Reference:
Oracle Database PL/SQL Packages and Types Reference
Oracle Data Guard Concepts and Administration Guide

The rate of SQL apply on a logical standby database can be influenced by:
* A: The number of PREPARER processes (which seems to be a typographical error and should read as PREPARER or similar) which prepare the redo data for the applier processes.
* B: The number of coordinator processes on the standby database instance which coordinate the SQL apply activities.
* C: The number of full table scans performed by SQL apply since full table scans can be resource-intensive and slow down the apply rate.
* E: The number of applier processes which apply the redo data to the logical standby database.
Option D is incorrect as the size of the undo tablespace on the logical standby database is more likely to affect the SQL apply lag rather than the rate of SQL apply.
Option F is incorrect because the size of the shared pool would typically not influence the rate of SQL apply.
The shared pool is more related to the caching of shared SQL and PL/SQL code and control structures.
References: Oracle's documentation on SQL Apply in Data Guard configurations discusses the factors affecting the performance of SQL Apply operations on logical standby databases.

Flashback Database is a feature that allows reverting a database to a previous point in time, which is extremely useful in various Data Guard configurations:
It may be used to flash back a physical standby that receives redo from a far sync instance (C): Flashback Database can be used on a physical standby database to revert it to a past point in time, even when it is receiving redo data from a far sync instance. This can be particularly useful to recover from logical corruptions or unwanted changes.
You can use it when real-time apply is enabled in case the physical standby suffers from logical corruption (D): Even when real-time apply is enabled, which allows redo data to be applied to the standby database as soon as it is received, Flashback Database can be used to revert the physical standby database to a point in time before the logical corruption occurred.
It may not be used to flash back a primary database after a failover to a physical standby (E): After a failover has occurred from a primary to a physical standby database, making the standby the new primary, Flashback Database cannot be used to revert the old primary database to a state before the failover because the failover operation makes irreversible changes to the database role and configuration.
Reference:
Oracle Database Backup and Recovery User's Guide
Oracle Data Guard Concepts and Administration

The execution of the UNSKIP procedure is designed to remove SQL Apply filters that have been previously set up on a logical standby database. Based on the provided statements, the UNSKIP procedure is directed to delete any SQL Apply filters for DML statements associated with objects in the 'HR' schema that start with 'EMP'. Since both SKIP procedures had the same schema name ('HR') and statement type ('DML'), and the UNSKIP procedure uses a wildcard (%) for the object name, it will successfully remove both of the SQL Apply filters for 'EMP_NEW' and 'EMP_OLD', as both object names match the pattern provided in the UNSKIP procedure.
Reference:
Oracle's Data Guard documentation and SQL Language Reference provide insights into managing SQL Apply filters on a logical standby database using the DBMS_LOGSTDBY package. This includes adding and removing filters through SKIP and UNSKIP procedures.