What is the difference between full backups and incremental backups?

• A. Full backups copy only changes since last backup
• B. Incremental backups copy all data
• C. Full backups copy all data; incremental backups copy only changes since the last backup
• D. Incremental backups store data in compressed form

Answer: (C)

Full backups copy all the data you’ve chosen to protect in one operation, giving you a complete snapshot. Incremental backups save only the data that has changed since the last backup, whether that last backup was a full one or another incremental one. Because of that, full backups are larger and take longer to run, but restoring from a full backup is simple and fast since you don’t need anything else. Restoring from incremental backups requires the most recent full backup plus every subsequent incremental backup to rebuild the current state, which can take more time but uses less storage in between full backups. This is why many strategies mix a full backup with regular incremental backups.

The idea that incremental backups copy all data isn’t correct, and the notion that full backups copy only changes isn’t correct either; compression is not the defining difference between the two.