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Data

Representation of facts, concepts, or instructions in a formalized manner suitable for communication, interpretation, or processing by humans or by automatic means. Any representations such as characters or analog quantities to which meaning is or might be assigned. A representation of facts, concepts, or instructions suitable for communication, interpretation, or processing by humans or computers.

Data-driven attack

A form of attack that is encoded in innocuous seeming data that is executed by a users or other software to implement an attack. In the case of firewalls, a data-driven attack is a concern because it may get through the firewall in data form and launch an attack against a system behind the firewall.

Datum

Any numerical or geometrical quantity or set of such quantities which may serve as reference or base for other quantities. Where the concept is geometric, the plural form is “datums” in contrast to the normal plural “data.”

DBA

Acronym for dominant battlespace awareness.

DBK

Acronym for dominant battlespace knowledge.

Deception

Those measures designed to mislead the enemy by manipulation, distortion, or falsification of evidence to induce him or her to react in a manner prejudicial to his or her interests.

Decision

In an estimate of the situation, a clear and concise statement of the line of action intended to be followed by the commander as the one most favorable to the successful accomplishment of the mission.

Defense information infrastructure (DII)

A label for the composite information assets of DoD (the American defense establishment).

Defensive counterinformation

Actions protecting the military information functions from the adversary.

Defragment

As modern file systems are used and files are deleted and created, the total free space becomes split into smaller noncontiguous blocks. Eventually new files being created, and old files being extended, cannot be stored each in a single contiguous block but become scattered across the file system. This degrades performance as multiple seek operations are required to access a single fragmented file. Defragmenting consolidates each existing file and the free space into a contiguous group of sectors. Access speed will be improved due to reduced seeking. A nearly full disk system will fragment more quickly. A disk should be defragmented before fragmenting reaches 10%.

Degradation of service

Any reduction (with respect to norms or expectations) in service processes’ reaction or response time, quantitative throughput, or quality parameters. This term is often used to denote the general set of service(s) impairment(s) that at the extreme (total degradation to a “zero state” with respect to the given parameters) constitutes an absolute denial of service. Note that (owing to operational constraints such as “time before timing out” settings) a disruptive tactic capable of only degrading service(s) may result in a complete denial of said service(s) from the perspective of the end user(s).

Denial of service

Action(s) that prevent any part of an AIS from functioning in accordance with its intended purpose. Denial of service attacks may include denying services or processes limited to one host machine. However, the term is most often invoked to connote action against a single host (or set of hosts), which results in the target’s inability to perform service(s) for other users— particularly over a network. One may consider denial of service to be the extreme case of degradation of service in which one or more normal functional parameters (response, throughput) get “zeroed out,” at least as far as the end user is concerned. It is important to note that “denial” is delineated with respect to whether the normal end user(s) can exploit the system or network as expected. Seen in this light, “denial” (like “degradation”) is descriptive of a functional outcome, and is not, therefore, definitive with respect to cause(s) (tactics effecting said result). Forms of attack not geared to “denial” per se may lead to “denial” as a corollary effect (when a system administrator’s actions in response to an intrusion attempt lead to a service outage). As such, “denial of service” is not a good criterion for categorizing attack tactics.

Denial time

The average length of time that an affected asset is denied to the organization. The temporal extent of operational malaise induced by a denial of service attack.

DII

Acronym for defense information infrastructure.

Direct information warfare

Changing the adversary’s information without involving the intervening perceptive and analytical functions.

Directed-energy protective measures

That division of directed-energy warfare involving actions taken to protect friendly equipment, facilities, and personnel to ensure friendly effective uses of the electromagnetic spectrum that are threatened by hostile directed-energy weapons and devices.

Directory

This is an index into the files on your disk. It acts as a hierarchy, and you will see the directory represented in Windows looking like manila folders.

Disk space

Disk space is the amount of storage space you’re allocated to use on the server, also server space and Web space. The more disk space you have, the bigger your Web site can be. It’s used to store everything related to your Web site such as your regular html files, images, multimedia files, anonymous ftp files, POP mail messages, CGI scripts, and any other files that make up your Web site.

DMA

Stands for direct access memory. DMA is a fast way of transferring data within a computer. Most devices require a dedicated DMA channel (so the number of DMA channels that are available may limit the number of peripherals that can be installed).

Domain name registration

A domain name is a textual address that is a unique identifier for your Web site that corresponds to your site’s numerical Internet Protocol (IP) address, and is usually related to your business, such as www.acmecatapults.com.

DRAM

Dynamic random access memory (see also SDRAM). A type of memory used in a PC for the main memory (such as your “32 Mbytes of RAM”). “Dynamic” refers to the memory’s memory of storage—basically storing the charge on a capacitor. Specialized types of DRAM (such as EDO memory) have been developed to work with today’s faster processors.

Driver

A program designed to interface a particular piece of hardware to an operating system or other software.

DOS

Disk operating system. Usually used as an abbreviation for MS-DOS, a microcomputer operating system developed by Microsoft.

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