CISA Practice Question: Information Systems Operations and Business Resilience
Which of the following backup types copies only data that has changed since the last full backup?
⚠ Common exam trap
Candidates often confuse 'differential' with 'incremental' because both copy changed data, but the key differentiator is the reference point: differential uses the last full backup, while incremental uses the last backup of any type.
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
A differential backup copies all data that has changed since the last full backup, regardless of how many incremental backups have been performed. This means each differential backup contains all changes accumulated since the most recent full backup, making it larger than an incremental backup but faster to restore (requiring only the full backup plus the latest differential).
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Mirror backup
Why it's wrong here
Mirror creates an exact copy, not just changes.
- ✓
Differential backup
Why this is correct
Correct. Differential copies all changes since the last full backup.
- ✗
Full backup
Why it's wrong here
Full backup copies all data regardless of changes.
- ✗
Incremental backup
Why it's wrong here
Incremental copies changes since the last backup of any type.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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