Explanation/Reference:
Explanation:
DNS primarily uses User Datagram Protocol (UDP) on port number 53 to serve requests.DNS queries consist of a single UDP request from the client followed by a single UDP reply from the server.
Incorrect Answers:
A: FTP uses the TCP protocol.
B: Telnet uses the TCP protocol.
C: SMTP uses the TCP protocol.
References:
https://en.wikipedia.org/wiki/Domain_Name_System

Explanation/Reference:
Explanation:
In a Smurf attack the attacker sends an ICMP ECHO REQUEST packet with a spoofed source address to a victim's network broadcast address. This means that each system on the victim's subnet receives an ICMP ECHO REQUEST packet. Each system then replies to that request with an ICMP ECHO REPLY packet to the spoof address provided in the packets-which is the victim's address.
Incorrect Answers:
A: A Syn flood attack does not involve spoofing and ICMP ECHO broadcasts. A SYN flood is a form of denial-of-service attack in which an attacker sends a succession of SYN requests to a target's system in an attempt to consume enough server resources to make the system unresponsive to legitimate traffic.
C: A ping of death is a type of attack on a computer system that involves sending a malformed or otherwise malicious ping to a computer. It could cause a buffer overflow, but it does not involve ICMP ECHO broadcast packets D: A DoS attack does not use spoofing or ICMP ECHO broadcasts. In a DoS attack the attacker sends a succession of SYN requests to a target's system in an attempt to consume enough server resources to make the system unresponsive to legitimate traffic.
References:
Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, New York, 2013, p. 587

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).