Which statement accurately describes differential backups?

Which statement accurately describes differential backups?

• A. It copies files that were changed since the last full backup.
• B. It copies all files since the last backup regardless of type.
• C. It copies only files changed since the last incremental backup.
• D. It copies only metadata without file contents.

Answer: (A)

Differential backups capture every file that has changed since the most recent full backup. This means each differential includes all the changes accumulated from that baseline, not just since the last backup in general. When you restore, you bring back the full backup first, then apply the latest differential to bring everything up to date. This approach sits between a full backup and incremental backups: it preserves a complete set of changes since the baseline, which makes restores relatively quick because you only need the last full backup plus the most recent differential. It also avoids re-copying all data every time, unlike a full backup done each time, while still limiting the number of separate backup sets compared to many increments. The other statements don’t fit because one describes copying all files since the last backup regardless of whether they changed, which isn’t differential behavior. Another describes changes since the last incremental backup, which is how incremental backups work, not differential. And another suggests only metadata is copied, which omits file contents entirely.