Which of the following backup types enables you to perform a system restore in the least amount of time?

A.
Full backup

B.
Incremental backup

C.
Differential backup

D.
All of the above.

Explanation:
A full backup allows you to perform the restore in the least quantity of time. This is due to a full backup backing up all contents of the server or disk. This can be useful in situations where you need to perform a restore after a server system failure.
Incorrect Answers:
B: With incremental backups, to perform a restore after a server system failure, you need to restore the most recent full backup first. You then need to perform a sequential restoration using each incremental backup that was performed since the last full backup.
C: With differential backups, to perform a restore after a server system failure, you need to restore the most recent full backup first. After this, you need to either perform a sequential restoration using each incremental backup that was performed since the last full backup, or use a differential backup. Using a differential backup in the system restoration process takes longer than using an incremental backup because every changed file since the last full backup is included in the backup.
D: Full backup is the correct answer.
References:
Charles J. Brooks, Server+ Certification Exam Cram 2 (Exam SK0-002), QUE Publishing, Indianapolis, 2006, pp. 378-380.