Explanation/Reference:
Although a auditing is a part of corporate security, it in no way supercedes the requirments for a disaster recovery plan. All others can be blamed for a plan going out of date.
Source: HARRIS, Shon, All-In-One CISSP Certification Exam Guide, McGraw-Hill/Osborne, 2002, chapter
9: Disaster Recovery and Business continuity (page 609).

Section: Access Control
Explanation/Reference:
The Clark-Wilson model uses separation of duties, which divides an operation into different parts and requires different users to perform each part. This prevents authorized users from making unauthorized modifications to data, thereby protecting its integrity.
The Clark-Wilson integrity model provides a foundation for specifying and analyzing an integrity policy for a computing system.
The model is primarily concerned with formalizing the notion of information integrity. Information integrity is maintained by preventing corruption of data items in a system due to either error or malicious intent. An integrity policy describes how the data items in the system should be kept valid from one state of the system to the next and specifies the capabilities of various principals in the system. The model defines enforcement rules and certification rules.
The model's enforcement and certification rules define data items and processes that provide the basis for an integrity policy. The core of the model is based on the notion of a transaction.
A well-formed transaction is a series of operations that transition a system from one consistent state to another consistent state.
In this model the integrity policy addresses the integrity of the transactions.
The principle of separation of duty requires that the certifier of a transaction and the implementer be different entities.
The model contains a number of basic constructs that represent both data items and processes that operate on those data items. The key data type in the Clark-Wilson model is a Constrained Data Item (CDI). An Integrity Verification Procedure (IVP) ensures that all CDIs in the system are valid at a certain state.
Transactions that enforce the integrity policy are represented by Transformation Procedures (TPs). A TP takes as input a CDI or Unconstrained Data Item (UDI) and produces a CDI. A TP must transition the system from one valid state to another valid state. UDIs represent system input (such as that provided by a user or adversary). A TP must guarantee (via certification) that it transforms all possible values of a UDI to a "safe" CDI.
In general, preservation of data integrity has three goals:
Prevent data modification by unauthorized parties
Prevent unauthorized data modification by authorized parties
Maintain internal and external consistency (i.e. data reflects the real world) Clark-Wilson addresses all three rules but BIBA addresses only the first rule of intergrity.
References:
HARRIS, Shon, All-In-One CISSP Certification Fifth Edition, McGraw-Hill/Osborne, Chapter 5: Security Architecture and Design (Page 341-344).
and
http://en.wikipedia.org/wiki/Clark-Wilson_model

Explanation/Reference:
While the purpose of systems in the DMZ is to allow public access to certain internal network resources (EMAIL, DNS, Web), it is a good practice to restrict that access to the minimum necessary to provide those services through use of a firewall.
In computer security, a DMZ or Demilitarized Zone (sometimes referred to as a perimeter network) is a physical or logical subnetwork that contains and exposes an organization's external-facing services to a larger and untrusted network, usually the Internet. The purpose of a DMZ is to add an additional layer of security to an organization's local area network (LAN); an external attacker only has direct access to equipment in the DMZ, rather than any other part of the network. The name is derived from the term
"demilitarized zone", an area between nation states in which military operation is not permitted.
The following are incorrect answers:
"Right in front of your first Internet facing firewall" While the purpose of systems in the DMZ is to allow public access to certain internal network resources (EMAIL, DNS, Web), it is a good practice to restrict that access to the minimum necessary to provide those services through use of a firewall.
"Right behind your first network active firewall" This is an almost-right-sounding answer meant to distract the unwary.
"Right behind your first network passive Internet http firewall" This is an almost-right-sounding answer meant to distract the unwary.
References:
CBK, p. 434
and
AIO3, p. 483
and
http://en.wikipedia.org/wiki/DMZ_%28computing%29

Explanation/Reference:
Source: TIPTON, Harold F. & KRAUSE, MICKI, Information Security Management Handbook, 4th Edition, Volume 2, 2001, CRC Press, NY, Page 33.