Explanation/Reference:
Anything based on a fixed IP address would be a problem for mobile users because their location and its associated IP address can change from one time to the next. Many providers will assign a new IP every time the device would be restarted. For example an insurance adjuster using a laptop to file claims online.
He goes to a different client each time and the address changes every time he connects to the ISP.
NOTE FROM CLEMENT:
The term MOBILE in this case is synonymous with Road Warriors where a user is contantly traveling and changing location. With smartphone today that may not be an issue but it would be an issue for laptops or WIFI tablets. Within a carrier network the IP will tend to be the same and would change rarely. So this question is more applicable to devices that are not cellular devices but in some cases this issue could affect cellular devices as well.
The following answers are incorrect:
mechanism with reusable password. This is incorrect because reusable password mechanism would not present a problem for mobile users. They are the least secure and change only at specific interval.
one-time password mechanism. This is incorrect because a one-time password mechanism would not present a problem for mobile users. Many are based on a clock and not on the IP address of the user.
challenge response mechanism. This is incorrect because challenge response mechanism would not present a problem for mobile users.

All other properties above apply to the Rijndael algorithm, chosen as the AES standard to replace DES.
The AES algorithm is capable of using cryptographic keys of 128, 192, and 256 bits to encrypt and decrypt data in blocks of 128 bits. Rijndael was designed to handle additional block sizes and key lengths, however they are not adopted in the AES standard.
IDEA cipher algorithm operates on 64-bit plaintext blocks and uses a 128 bit key.
Reference(s) used for this question:
http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf and http://en.wikipedia.org/wiki/Advanced_Encryption_Standard

Explanation/Reference:
An identity-based access control is a type of Discretionary Access Control (DAC) that is based on an individual's identity.
DAC is good for low level security environment. The owner of the file decides who has access to the file.
If a user creates a file, he is the owner of that file. An identifier for this user is placed in the file header and/ or in an access control matrix within the operating system.
Ownership might also be granted to a specific individual. For example, a manager for a certain department might be made the owner of the files and resources within her department. A system that uses discretionary access control (DAC) enables the owner of the resource to specify which subjects can access specific resources.
This model is called discretionary because the control of access is based on the discretion of the owner.
Many times department managers, or business unit managers , are the owners of the data within their specific department. Being the owner, they can specify who should have access and who should not.
Reference(s) used for this question:
Harris, Shon (2012-10-18). CISSP All-in-One Exam Guide, 6th Edition (p. 220). McGraw-Hill . Kindle Edition.

DES is a block encryption algorithm using 56-bit keys and 64-bit blocks that are divided in half and each character is encrypted one at a time. The characters are put through 16 rounds of transposition and substitution functions. Triple DES uses 48 rounds. Source: WALLHOFF, John, CBK#5 Cryptography (CISSP Study Guide), April 2002 (page 3).

Explanation/Reference:
The question was asking for a TRUE statement and the only correct statement is "Kerberos does not address availability".
Kerberos addresses the confidentiality and integrity of information. It does not directly address availability.
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 42).