Incremental backups only backup changed data (changes archive bit to not
backup again if not changed).
Although the incremental backup is fastest to backup, it is usually more time consuming for
the restore process.
In some cases, the window available for backup may not be long enough to backup all the
data on the system during each backup. In that case, differential or incremental backups
may be more appropriate.
In an incremental backup, only the files that changed since the last backup will be backed
up.
In a differential backup, only the files that changed since the last full backup will be backed
up.
In general, differentials require more space than incremental backups while incremental
backups are faster to perform. On the other hand, restoring data from incremental backups
requires more time than differential backups. To restore from incremental backups, the last
full backup and all of the incremental backups performed are combined. In contrast,
restoring from a differential backup requires only the last full backup and the latest
differential.
The following are incorrect answers:
Differential backups backup all data since the last full backup (does not reset archive bit)
Full backups backup all selected data, regardless of archive bit, and resets the archive bit.
Disk mirroring is not considered as a backup type.
Reference(s) used for this question:
Hernandez CISSP, Steven (2012-12-21). Official (ISC)2 Guide to the CISSP CBK, Third
Edition ((ISC)2 Press) (Kindle Locations 20385-20390). Auerbach Publications. Kindle
Edition.
and
HARRIS, Shon, All-In-One CISSP Certification Exam Guide, McGraw-Hill/Osborne, 2002,
chapter 9: Disaster Recovery and Business continuity (page 618).