What is a Differential Backup? SSCP Backup Concepts

Quick Answer

This is a differential backup because the defining trait described in the scenario, backing up all data changed since the last full backup every time regardless of what happened on the days in between, is precisely what separates differential backups from incremental ones. A full backup on Sunday captures everything, establishing the baseline that every subsequent backup measures against. From that point forward, a differential backup always looks back to that same full backup as its reference point, capturing all changes accumulated since Sunday, which means each day's differential backup grows progressively larger than the day before, since it's re-capturing everything the previous differential already captured plus whatever changed since then. This is different from an incremental backup, which instead references only the most recent backup of any kind and resets its tracking after each run, resulting in smaller, faster backups that only capture that day's changes, but requiring every incremental backup since the last full to be restored in sequence to reconstruct the data. Differential backups trade some storage efficiency for a simpler, faster restore process, since recovery only ever needs the last full backup plus the single most recent differential. When a question describes a backup strategy that references the same full backup on every subsequent run, that's the differential pattern; if it instead resets and references only the previous day's backup, that's incremental.