In a backup strategy, which backup type copies only data that has changed since the last full backup?

In a backup strategy, which backup type copies only data that has changed since the last full backup?

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

Answer: (C)

Understanding how backup types track changes helps you see why this choice fits. A differential backup copies only the data that has changed since the last full backup, so it accumulates all changes made after that baseline. That makes each differential backup larger than the previous one until the next full backup resets the baseline. In contrast, an incremental backup copies only what changed since the most recent backup of any type, which keeps each run smaller but requires chaining backups for restores. A full backup copies everything at once, and a mirror backup is a direct, exact copy of the current state. So, the backup type that copies only data changed since the last full backup is the differential backup.

Understanding how backup types track changes helps you see why this choice fits. A differential backup copies only the data that has changed since the last full backup, so it accumulates all changes made after that baseline. That makes each differential backup larger than the previous one until the next full backup resets the baseline. In contrast, an incremental backup copies only what changed since the most recent backup of any type, which keeps each run smaller but requires chaining backups for restores. A full backup copies everything at once, and a mirror backup is a direct, exact copy of the current state. So, the backup type that copies only data changed since the last full backup is the differential backup.