Section: Access Control
Explanation/Reference:
A spoofing attack is when an attempt is made to gain access to a computer system by posing as an authorized user or system. Spamming refers to sending out or posting junk advertising and unsolicited mail. A smurf attack is a type of denial-of-service attack using PING and a spoofed address. Sniffing refers to observing packets passing on a network.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 3: Telecommunications and Network Security (page
77).

Layer 5 of the OSI model is the Session Layer. This layer provides a logical
persistent connection between peer hosts. A session is analogous to a conversation that is
necessary for applications to exchange information.
The session layer is responsible for establishing, managing, and closing end-to-end
connections, called sessions, between applications located at different network endpoints.
Dialogue control management provided by the session layer includes full-duplex, half-
duplex, and simplex communications. Session layer management also helps to ensure that
multiple streams of data stay synchronized with each other, as in the case of multimedia
applications like video conferencing, and assists with the prevention of application related
data errors.
The session layer is responsible for creating, maintaining, and tearing down the session.
Three modes are offered:
(Full) Duplex: Both hosts can exchange information simultaneously, independent of each
other.
Half Duplex: Hosts can exchange information, but only one host at a time.
Simplex: Only one host can send information to its peer. Information travels in one direction
only.
Another aspect of performance that is worthy of some attention is the mode of operation of
the network or connection. Obviously, whenever we connect together device A and device
B, there must be some way for A to send to B and B to send to A. Many people don't
realize, however, that networking technologies can differ in terms of how these two
directions of communication are handled. Depending on how the network is set up, and the
characteristics of the technologies used, performance may be improved through the
selection of performance-enhancing modes.
Basic Communication Modes of Operation
Let's begin with a look at the three basic modes of operation that can exist for any network
connection, communications channel, or interface. Simplex Operation
In simplex operation, a network cable or communications channel can only send information in one direction; it's a "one-way street". This may seem counter-intuitive: what's the point of communications that only travel in one direction? In fact, there are at least two different places where simplex operation is encountered in modern networking.
The first is when two distinct channels are used for communication: one transmits from A to B and the other from B to A. This is surprisingly common, even though not always obvious. For example, most if not all fiber optic communication is simplex, using one strand to send data in each direction. But this may not be obvious if the pair of fiber strands are combined into one cable.
Simplex operation is also used in special types of technologies, especially ones that are asymmetric. For example, one type of satellite Internet access sends data over the satellite only for downloads, while a regular dial-up modem is used for upload to the service provider. In this case, both the satellite link and the dial-up connection are operating in a simplex mode. Half-Duplex Operation
Technologies that employ half-duplex operation are capable of sending information in both directions between two nodes, but only one direction or the other can be utilized at a time. This is a fairly common mode of operation when there is only a single network medium (cable, radio frequency and so forth) between devices.
While this term is often used to describe the behavior of a pair of devices, it can more generally refer to any number of connected devices that take turns transmitting. For example, in conventional Ethernet networks, any device can transmit, but only one may do so at a time. For this reason, regular (unswitched) Ethernet networks are often said to be "half-duplex", even though it may seem strange to describe a LAN that way. Full-Duplex Operation
In full-duplex operation, a connection between two devices is capable of sending data in both directions simultaneously. Full-duplex channels can be constructed either as a pair of simplex links (as described above) or using one channel designed to permit bidirectional simultaneous transmissions. A full-duplex link can only connect two devices, so many such links are required if multiple devices are to be connected together.
Note that the term "full-duplex" is somewhat redundant; "duplex" would suffice, but everyone still says "full-duplex" (likely, to differentiate this mode from half-duplex).
For a listing of protocols associated with Layer 5 of the OSI model, see below:
ADSP - AppleTalk Data Stream Protocol ASP - AppleTalk Session Protocol
H.245 - Call Control Protocol for Multimedia Communication ISO-SP OSI session-layer protocol (X.225, ISO 8327) iSNS - Internet Storage Name Service
The following are incorrect answers:
Synchronous and Asynchronous are not session layer modes.
Half simplex does not exist. By definition, simplex means that information travels one way only, so half-simplex is a oxymoron.
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 5603-5636). Auerbach Publications. Kindle Edition. and http://www.tcpipguide.com/free/t_SimplexFullDuplexandHalfDuplexOperation.htm and http://www.wisegeek.com/what-is-a-session-layer.htm

Explanation/Reference:
Cryptology is the science that includes both cryptography and cryptanalysis and is not directly concerned with key management. Cryptology is the mathematics, such as number theory, and the application of formulas and algorithms, that underpin cryptography and cryptanalysis.
The following are all concerned with Key Management which makes them the wrong choices:
Internet Security Association Key Management Protocol (ISAKMP) is a key management protocol used by IPSec. ISAKMP (Internet Security Association and Key Management Protocol) is a protocol defined by RFC 2408 for establishing Security Associations (SA) and cryptographic keys in an Internet environment.
ISAKMP only provides a framework for authentication and key exchange. The actual key exchange is done by the Oakley Key Determination Protocol which is a key-agreement protocol that allows authenticated parties to exchange keying material across an insecure connection using the Diffie-Hellman key exchange algorithm.
Diffie-Hellman and one variation of the Diffie-Hellman algorithm called the Key Exchange Algorithm (KEA) are also key exchange protocols. Key exchange (also known as "key establishment") is any method in cryptography by which cryptographic keys are exchanged between users, allowing use of a cryptographic algorithm. Diffie-Hellman key exchange (D-H) is a specific method of exchanging keys. It is one of the earliest practical examples of key exchange implemented within the field of cryptography. The Diffie- Hellman key exchange method allows two parties that have no prior knowledge of each other to jointly establish a shared secret key over an insecure communications channel. This key can then be used to encrypt subsequent communications using a symmetric key cipher.
Reference(s) used for this question:
Mike Meyers CISSP Certification Passport, by Shon Harris and Mike Meyers, page 228.
It is highlighted as an EXAM TIP. Which tells you that it is a must know for the purpose of the exam.
HARRIS, Shon, All-In-One CISSP Certification Exam Guide, McGraw-Hill/Osborne, Fifth Edition, Chapter
8: Cryptography (page 713-715).
and
https://en.wikipedia.org/wiki/ISAKMP
and
http://searchsecurity.techtarget.com/definition/cryptology

Section: Risk, Response and Recovery
Explanation
Explanation/Reference:
Disaster Recovery should never be considered a discretionary expense. It is far too important a task. In order to maintain the continuity of the business Disaster Recovery should be a commitment of and by the organization.
A discretionary fixed cost has a short future planning horizon-under a year. These types of costs arise from annual decisions of management to spend in specific fixed cost areas, such as marketing and research. DR would be an ongoing long term committment not a short term effort only.
A committed fixed cost has a long future planning horizon- more than on year. These types of costs relate to a company's investment in assets such as facilities and equipment. Once such costs have been incurred, the company is required to make future payments.
The following answers are incorrect:
committed expense. Is incorrect because Disaster Recovery should be a committed expense.
enforcement of legal statutes. Is incorrect because Disaster Recovery can include enforcement of legal statutes. Many organizations have legal requirements toward Disaster Recovery.
compliance with regulations. Is incorrect because Disaster Recovery often means compliance with regulations.
Many financial institutions have regulations requiring Disaster Recovery Plans and Procedures.

Section: Risk, Response and Recovery
Explanation/Reference:
Failure of a contingency plan is usually management failure to exhibit ongoing interest and concern about the BCP/DRP effort, and to provide financial and other resources as needed. Lack of management support will result in a lack awareness and training.
Source: ANDRESS, Mandy, Exam Cram CISSP, Coriolis, 2001, Chapter 9: Business Continuity Planning (BCP) and Disaster Recovery Planning (DRP) (page 163).