CompTIA Tech+ (FC0-U71)Data and Database FundamentalsHard
A server performs a full backup every Sunday and a differential backup every other day. On Thursday, the server fails and all data is lost. Which backup sets are needed to fully restore the data?
- ASunday's full backup and Wednesday's differential backup only
- BAll differential backups from Monday through Thursday
- CSunday's full backup and Thursday's differential backup
- DOnly Thursday's differential backup
Show answer & explanationAnswer & explanation
Correct answer: C. Sunday's full backup and Thursday's differential backup
A differential backup captures all changes made since the last full backup, so each differential backup file grows cumulatively larger and contains everything needed since Sunday. To restore, only the full backup plus the most recent differential backup (Thursday's) are required.
Why the other options are wrong
- A. Wednesday's backup would be missing changes made on Thursday.
- B. Differential backups are cumulative, so only the most recent one is needed, not all of them.
- D. Differential backups alone don't contain data unchanged since the full backup.
Differential Backup
A differential backup captures all changes made since the last full backup, growing larger each day until the next full backup resets the cycle.
- Backs up changes since the last FULL backup
- Restoration needs only the full backup plus the latest differential
- Grows larger over time between full backups
Memory trick: Differential = keeps 'Adding the Difference' since the full backup