220-1102 Question 694
Single answerDifferentialA small accounting office performs a full backup of its file server every Sunday night and a differential backup every weekday evening. On Thursday morning, the server’s drive fails and must be restored to a replacement drive. To recover the most recent data using the fewest backup sets, which backups should the technician restore?
- A
Restore only the most recent differential backup from Wednesday evening
- B
Restore the Sunday full backup, then restore the most recent differential backup from Wednesday evening
- C
Restore the Sunday full backup, then restore each differential backup from Monday, Tuesday, and Wednesday in order
- D
Restore the Sunday full backup, then restore each incremental backup from Monday through Wednesday
Show answer and explanation
Correct answer: B
Explanation
Differential backups capture all data changed since the last full backup. In this scenario, Sunday is the last full backup, and Wednesday evening is the latest completed differential before the Thursday failure. Best practice for recovery is therefore to restore the Sunday full backup first and then the Wednesday differential backup. This approach minimizes the number of backup sets required while still recovering the most recent available data. By contrast, incremental backup strategies require the last full backup plus every incremental backup since that full backup. This distinction is a core backup-and-recovery concept commonly covered in CompTIA A+ Core 2 objectives related to backup methods, disaster recovery, and data restoration procedures.
- A. Incorrect.
Incorrect. A differential backup does not contain the complete baseline by itself. It stores all changes made since the last full backup, so the full backup is still required first during restoration.
- B. Correct.
Correct. The proper restore process for differential backups is to restore the last full backup and then the most recent differential backup. Because each differential includes all changes since the last full backup, only these two backup sets are needed.
- C. Incorrect.
Incorrect. This describes a common misunderstanding between differential and incremental backups. With differential backups, you do not need to restore each daily differential in sequence; the latest differential already includes the changes from the earlier differentials since the last full backup.
- D. Incorrect.
Incorrect. This option mixes backup types. Incremental backups require restoring the last full backup plus every incremental backup made after it. The scenario specifically states that weekday backups are differential, not incremental.