Section: Network and Telecommunications
Explanation/Reference:
Bootstrap Protocol (BootP) is an Internet Layer protocol that enables a workstation to boot without requiring a hard or floppy disk drive. Reverse Address Resolution Protocol (RARP) is a TCP/IP protocol that permits a physical address, such as an Ethernet address, to be translated into an IP address. Address Resolution Protocol (ARP) is a TCP/IP protocol that permits an IP address to be translated into a physical address.
Classless Inter-Domain Routing (CIDR) is a new IP addressing scheme.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 88.

Explanation/Reference:
In the lattice model, users are assigned security clearences and the data is classified. Access decisions are made based on the clearence of the user and the classification of the object. Lattice-based access control is an essential ingredient of formal security models such as Bell-LaPadula, Biba, Chinese Wall, etc.
The bounds concept comes from the formal definition of a lattice as a "partially ordered set for which every pair of elements has a greatest lower bound and a least upper bound." To see the application, consider a file classified as "SECRET" and a user Joe with a security clearence of "TOP SECRET." Under Bell- LaPadula, Joe's "least upper bound" access to the file is "READ" and his least lower bound is "NO WRITE" (star property).
Role-based access control is incorrect. Under RBAC, the access is controlled by the permissions assigned to a role and the specific role assigned to the user.
Biba access control is incorrect. The Biba integrity model is based on a lattice structure but the context of the question disqualiifes it as the best answer.
Content-dependent access control is incorrect. In content dependent access control, the actual content of the information determines access as enforced by the arbiter.
References:
CBK, pp. 324-325.
AIO3, pp. 291-293. See aprticularly Figure 5-19 on p. 293 for an illustration of bounds in action.

Explanation/Reference:
A communication channel that allows transfer of information in a manner that violates the system's security policy.
A covert channel is a way for an entity to receive information in an unauthorized manner. It is an information flow that is not controlled by a security mechanism. This type of information path was not developed for communication; thus, the system does not properly protect this path, because the developers never envisioned information being passed in this way.
Receiving information in this manner clearly violates the system's security policy. The channel to transfer this unauthorized data is the result of one of the following conditions:* Oversight in the development of the product
* Improper implementation of access controls
* Existence of a shared resource between the two entities
* Installation of a Trojan horse
The following answers are incorrect:
An undocumented backdoor that has been left by a programmer in an operating system is incorrect because it is not a means by which unauthorized transfer of information takes place. Such backdoor is usually referred to as a Maintenance Hook.
An open system port that should be closed is incorrect as it does not define a covert channel.
A trojan horse is incorrect because it is a program that looks like a useful program but when you install it it would include a bonus such as a Worm, Backdoor, or some other malware without the installer knowing about it.
Reference(s) used for this question:
Shon Harris AIO v3 , Chapter-5 : Security Models & Architecture
AIOv4 Security Architecture and Design (pages 343 - 344)
AIOv5 Security Architecture and Design (pages 345 - 346)

Section: Access Control
Explanation/Reference:
According to the cited reference, of the given options, the Retina scan has the lowest user acceptance level as it is needed for the user to get his eye close to a device and it is not user friendly and very intrusive.
However, retina scan is the most precise with about one error per 10 millions usage.
Look at the 2 tables below. If necessary right click on the image and save it on your desktop for a larger view or visit the web site directly at https://sites.google.com/site/biometricsecuritysolutions/crossover-accuracy .
Biometric Comparison Chart


Biometric Aspect Descriptions
Reference(s) used for this question:
RHODES, Keith A., Chief Technologist, United States General Accounting Office, National Preparedness, Technologies to Secure Federal Buildings, April 2002 (page 10).
and
https://sites.google.com/site/biometricsecuritysolutions/crossover-accuracy