Which backup method is used if backup time is critical and tape space is at an extreme premium? 

Answer options:

A. Incremental backup method.
B. Differential backup method.
C. Full backup method.
D. Tape backup method.

A

Full Backup/Archival Backup - Complete/Full backup of every selected file on the system regardless of whether it has been backup recently.. This is the slowest of the backup methods since it backups all the data. Its however the fastest for restoring data. Incremental Backup - Any backup in which only the files that have been modified since last full back up are backed up. The archive attribute should be updated while backing up only modified files, which indicates that the file has been backed up. This is the fastest of the backup methods, but the slowest of the restore methods. Differential Backup - The backup of all data files that have been modified since the last incremental backup or archival/full backup. Uses the archive bit to determine what files have changed since last incremental backup or full backup. The files grows each day until the next full backup is performed clearing the archive attributes. This enables the user to restore all files changed since the last full backup in one pass. This is a more neutral method of backing up data since its not faster nor slower than the other two Easy Way To Remember each of the backup type properties: Backup SpeedRestore Speed - Full31 - Differential22 - Incremental13 - Legend:1 = Fastest 2 = Faster3 = Slowest Source: KRUTZ, Ronald L. & VINES, Russel
D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 69. and http://www.proprofs.com/mwiki/index.php/Full_Backup,_Incremental_%26_Differential_Backup