Updating records in multiple locations or copying an entire database to a remote location as a means to ensure the appropriate levels of fault-tolerance and redundancy is known as Database shadowing. Shadowing is the technique in which updates are shadowed in multiple locations. It is like copying the entire database on to a remote location.
Shadow files are an exact live copy of the original active database, allowing you to maintain live duplicates of your production database, which can be brought into production in the event of a hardware failure. They are used for security reasons: should the original database be damaged or incapacitated by hardware problems, the shadow can immediately take over as the primary database. It is therefore important that shadow files do not run on the same server or at least on the same drive as the primary database files.
The following are incorrect answers:
Data mirroring In data storage, disk mirroring is the replication of logical disk volumes onto separate physical hard disks in real time to ensure continuous availability. It is most commonly used in RAID 1. A mirrored volume is a complete logical representation of separate volume copies.
Backups In computing the phrase backup means to copy files to a second medium (a disk or tape) as a precaution in case the first medium fails. One of the cardinal rules in using computers is back up your files regularly. Backups are useful in recovering information or a system in the event of a disaster, else you may be very sorry :-(
Archiving is the storage of data that is not in continual use for historical purposes. It is the process of copying files to a long-term storage medium for backup.
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 27614-27626). Auerbach Publications. Kindle Edition.
http://en.wikipedia.org/wiki/Disk_mirroring http://www.webopedia.com/TERM/A/archive.html http://ibexpert.net/ibe/index.php?n=Doc.DatabaseShadow

Explanation/Reference:
Operational controls are controls over the hardware, the media used and the operators using these resources.
Operational controls are controls that are implemented and executed by people, they are most often procedures.
Backup and recovery, contingency planning and operations procedures are operational controls.
Auditing is considered an Administrative / detective control. However the actual auditing mechanisms in place on the systems would be consider operational controls.

A certification authority (CA) is a third party entity that issues digital
certificates (especially X.509 certificates) and vouches for the binding between the data
items in a certificate. An issuing authority could be considered a correct answer, but not the
best answer, since it is too generic.
Source: SHIREY, Robert W., RFC2828: Internet Security Glossary, may 2000.

The incremental backup method usually resets the archive bit on the files
after they have been backed up.
An Incremental Backup will backup all the files that have changed since the last Full
Backup (the first time it is run after a full backup was previously completed) or after an
Incremental Backup (for the second backup and subsequent backups) and sets the archive
bit to 0. This type of backup take less time during the backup phase but it will take more
time to restore.
The other answers are all incorrect choices.
The following backup types also exists:
Full Backup - All data are backed up. The archive bit is cleared, which means that it is set
to 0.
Differential Backup - Backup the files that have been modified since the last Full Backup.
The archive bit does not change. Take more time while the backup phase is performed and
take less time to restore.
Reference(s) used for this question:
KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten
Domains of Computer Security, 2001, John Wiley & Sons, Page 69.

Section: Analysis and Monitoring
Explanation/Reference:
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