Which backup type saves only data changed since the last full or incremental backup?

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

Answer: (A)

Incremental backups save only data that has changed since the last backup. After the initial full backup, each new backup records only the files that were added or modified since the previous backup (whether that previous backup was full or incremental). This makes incremental backups quick and storage-efficient because you aren’t duplicating unchanged data. To restore, you reconstruct from the last full backup and then apply each incremental in sequence to bring the data up to date.

In contrast, a full backup copies everything every time, which uses more space and time. A differential backup collects all changes since the last full backup, so its size grows over time. A mirror backup is an exact copy of the source at the backup moment and isn’t designed around a change-since-last-backup scheme.