In a backup plan where full backups occur weekly and hourly backups capture changes since the last backup of any type, which backup type is used every hour?

• A. Full
• B. Differential
• C. Incremental
• D. Mirror

Answer: (C)

Incremental backups store only what has changed since the last backup of any type (whether that last backup was full or incremental). In this plan, you have a weekly full backup and hourly backups that capture the changes since the previous backup, regardless of its type. That means each hour’s backup is a delta from the immediate prior backup, forming a chain you can apply in order to reconstruct the current state. This behavior is the hallmark of incremental backups: you start with the last full backup and then apply a series of small, successive changes.

Differential backups, by contrast, capture all changes since the last full backup, so each hourly differential would grow larger over time and you’d only need the last full backup plus the most recent differential to restore. A mirror would be an exact, up-to-date copy of the data, not a delta chain of hourly changes.