Which backup method copies only files that have changed since the last full backup, but does not clear the archive bit?
Correct Answer: A
One of the key item to understand regarding backup is the archive bit. The archive bit is used to determine what files have been backuped already. The archive bit is set if a file is modified or a new file is created, this indicates to the backup program that it has to be saved on the next backup. When a full backup is performed the archive bit will be cleared indicating that the files were backup. This allows backup programs to do an incremental or differential backup that only backs up the changes to the filesystem since the last time the bit was cleared Full Backup (or Reference Backup) A Full backup will backup all the files and folders on the drive every time you run the full backup. The archive bit is cleared on all files indicating they were all backuped. Advantages: All files from the selected drives and folders are backed up to one backup set. In the event you need to restore files, they are easily restored from the single backup set. Disadvantages: A full backup is more time consuming than other backup options. Full backups require more disk, tape, or network drive space. Incremental Backup An incremental backup provides a backup of files that have changed or are new since the last incremental backup. For the first incremental backup, all files in the file set are backed up (just as in a full backup). If you use the same file set to perform a incremental backup later, only the files that have changed are backed up. If you use the same file set for a third backup, only the files that have changed since the second backup are backed up, and so on. Incremental backup will clear the archive bit. Advantages: Backup time is faster than full backups. Incremental backups require less disk, tape, or network drive space. You can keep several versions of the same files on different backup sets. Disadvantages: In order to restore all the files, you must have all of the incremental backups available. It may take longer to restore a specific file since you must search more than one backup set to find the latest version of a file. Differential Backup A differential backup provides a backup of files that have changed since a full backup was performed. A differential backup typically saves only the files that are different or new since the last full backup. Together, a full backup and a differential backup include all the files on your computer, changed and unchanged. Differential backup do not clear the archive bits. Advantages: Differential backups require even less disk, tape, or network drive space than incremental backups. Backup time is faster than full or incremental backups. Disadvantages: Restoring all your files may take considerably longer since you may have to restore both the last differential and full backup. Restoring an individual file may take longer since you have to locate the file on either the differential or full backup. For more info see: http://support.microsoft.com/kb/136621 Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 69.
Question 42
Which of the following is not an example of a block cipher?
Correct Answer: D
RC4 is a proprietary, variable-key-length stream cipher invented by Ron Rivest for RSA Data Security, Inc. Skipjack, IDEA and Blowfish are examples of block ciphers. Source: SHIREY, Robert W., RFC2828: Internet Security Glossary, may 2000.
Question 43
Which of the following access control models requires security clearance for subjects?
Correct Answer: D
With mandatory access control (MAC), the authorization of a subject's access to an object is dependant upon labels, which indicate the subject's clearance. Identity-based access control is a type of discretionary access control. A role-based access control is a type of non-discretionary access control. Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 2: Access control systems (page 33).
Question 44
Much like the layers of an onion, ______________ is a comprehensive set of security solutions layered to provide the best protection.
Correct Answer: C
Question 45
What is called the probability that a threat to an information system will materialize?
Correct Answer: B
The answer: Risk: The potential for harm or loss to an information system or network; the probability that a threat will materialize.
