Which files must be synchronized for a database to open?

Answer: Control files, data files and redo log-files must be synchronized

Explanation:

While the process of opening of the database takes place, there is the certain requirement of acknowledging the state and instance of the database. This is a major step to start up the process and thus synchronization is done.

The synchronization process takes place in the control file, redo log-file and the data files. These files operate after the database is opened up or started.