What is a Differential Backup? SSCP Backup Concepts
A company uses a backup strategy that backs up all data every Sunday and backs up only data that has changed since the last full backup on other days. This is an example of which backup type?
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.
⚠ Common exam trap
Many candidates confuse 'changed since the last full backup' (differential) with 'changed since the last backup' (incremental), causing candidates to mistakenly select incremental backup when the key phrase 'since the last full backup' clearly indicates differential.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Differential backup
The described strategy backs up all data on Sunday (a full backup) and then on other days backs up only data that has changed since the last full backup. This is the defining characteristic of a differential backup: it always references the most recent full backup, not the previous day's backup. Unlike incremental backups, differential backups do not reset the archive bit after each run, so each differential backup grows in size until the next full backup.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Full backup
Why it's wrong here
A full backup captures all selected data every run, so it cannot explain the daily sets containing only data changed since Sunday. It is tempting because Sunday's job genuinely is a full backup, but the question asks about the overall strategy, which is differential, not full.
- ✓
Differential backup
Why this is correct
Differential backups copy every change made since the last full backup, so Sunday's full plus each day's cumulative changes matches this description. Incremental backups would capture only changes since the previous backup, which the stem explicitly excludes.
- ✗
Copy backup
Why it's wrong here
A copy backup duplicates selected data without resetting the archive bit or altering the existing backup schedule, so it cannot describe a recurring Sunday-full plus daily-changed pattern. It is tempting as a one-off snapshot before risky maintenance, but it plays no role in the differential cycle the stem describes.
- ✗
Incremental backup
Why it's wrong here
Incremental backups capture everything changed since the last backup of any type, so Monday's set would only hold Sunday-night changes, not all changes since Sunday's full. It is tempting because incrementals are the classic space-saving daily method, but the stem's "since the last full backup" describes a differential backup.
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Same concept, more angles
3 more ways this is tested on SSCP
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which of the following backup methods copies all data that has changed since the last full backup, regardless of any intermediate backups?
easy- ✓ A.Differential backup
- B.Full backup
- C.Incremental backup
- D.Snapshot backup
Why A: A differential backup copies all data that has changed since the last full backup, regardless of any intermediate backups. This means each differential backup grows in size as it accumulates all changes made since the last full backup, making it distinct from incremental backups which only capture changes since the last backup of any type.
Variation 2. Which backup type copies all data that has changed since the last full backup, regardless of subsequent backups?
easy- A.Incremental backup
- B.Snapshot backup
- ✓ C.Differential backup
- D.Full backup
Why C: A differential backup copies all data that has changed since the last full backup, regardless of any intermediate backups. This means each differential backup grows in size as it accumulates all changes made since the last full backup, making it distinct from incremental backups which only capture changes since the last backup of any type.
Variation 3. Which backup type copies all data that has changed since the last full backup, regardless of any incremental backups?
easy- A.Synthetic full backup
- B.Full backup
- ✓ C.Differential backup
- D.Incremental backup
Why C: A differential backup copies all data that has changed since the last full backup, regardless of any intermediate incremental backups. This means each differential backup grows in size as it accumulates all changes made after the last full backup, making it distinct from incremental backups which only capture changes since the last backup of any type.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SSCP practice question is part of Courseiva's free ISC2 certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SSCP exam.