B: Remastering is the term used that describes the operation whereby a node attempting recovery tries to own or master the resource(s) that were once mastered by another instance prior to the failure. When one instance leaves the cluster, the GRD of that instance needs to be redistributed to the surviving nodes. RAC uses an algorithm called lazy remastering to remaster only a minimal number of resources during a reconfiguration.
D: Using the SHUTDOWN TRANSACTIONAL command with the LOCAL option is useful to shut down a particular Oracle RAC database instance. Transactions on other instances do not block this operation.
C: Recovery from instance failure is automatic, requiring no DBA intervention. In case of instance failure, a surviving instance can read the redo logs of the failed instance.
For example, when using the Oracle Parallel Server, another instance performs instance recovery for the failed instance. In single-instance configurations, Oracle performs crash recovery for a database when the database is restarted, that is, mounted and opened to a new instance. The transition from a mounted state to an open state automatically triggers crash recovery, if necessary.