Explanation:
The recovery catalo is not updated when a lo switch occurs, when a log file is archived, or when datafiles or redo logs are added. Thus, the RESYNC CATALOG command must periodically be executed to keep the recovery catalog in line with the production database. This command is executed automatically when a database is registered and after a backup, recovery, or restoration.
Incorrect Answers:
1: This command is not used for alert log records.
3: This command is not used for rollback segment records.
Oracle 8, DBA Certification Exam Guide, Jason S. Couchman, p. 623
Chapter 13: Using Recovery Manager for Backups

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