Section: Risk, Response and Recovery
Explanation/Reference:
A security program should use a top-down approach, meaning that the initiation, support, and direction come from top management; work their way through middle management; and then reach staff members.
In contrast, a bottom-up approach refers to a situation in which staff members (usually IT ) try to develop a security program without getting proper management support and direction. A bottom-up approach is commonly less effective, not broad enough to address all security risks, and doomed to fail.
A top-down approach makes sure the people actually responsible for protecting the company's assets (senior management) are driving the program.
The following are incorrect answers:
The Delphi approach is incorrect as this is for a brainstorming technique.
The bottom-up approach is also incorrect as this approach would be if the IT department tried to develop a security program without proper support from upper management.
The technology approach is also incorrect as it does not fit into the category of best answer.
Reference(s) used for this question:
Harris, Shon (2012-10-18). CISSP All-in-One Exam Guide, 6th Edition (p. 63). McGraw-Hill. Kindle Edition.

Explanation/Reference:
If any server in the cluster crashes, processing continues transparently, however, the cluster suffers some performance degradation. This implementation is sometimes called a "server farm." Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 67.

Section: Network and Telecommunications
Explanation/Reference:
DNS relies on connectionless UDP whereas services like FTP, Telnet and SMTP rely on TCP.
Source: ROTHKE, Ben, CISSP CBK Review presentation on domain 2, August 1999.

Explanation/Reference:
NSA took the 128-bit algorithm Lucifer that IBM developed, reduced the key size to 64 bits and with that developed DES.
The following answers are incorrect:
Twofish. This is incorrect because Twofish is related to Blowfish as a possible replacement for DES.
Skipjack. This is incorrect, Skipjack was developed after DES by the NSA .
Brooks-Aldeman. This is incorrect because this is a distractor, no algorithm exists with this name.

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).