Computer/System Terms - D
data at rest (DAR) - (Data which is being stored, or resides in storage, in contrast to data which is being processed, edited, or transferred, normally on external or auxiliary storage devices, such as hard disk drives (HDD), solid-state drives (SSD), optical discs (CD/DVD), or even on magnetic tape.)
data acquisition servers (DAS) - (Backend devices, which are part of a Supervisory Control and Data Acquisition (SCADA) system used for controlling large-scale physical processes, such as power grids, which receive all data from system endpoints through a telemetry system and perform whatever correlation or analysis needed.)
Data Center Firewall (DCFW) - (A firewall - program or dedicated hardware device that inspects network traffic passing through it and denies or permits that traffic based on a set of rules determined at configuration - designed for, or dedicated to, the protection of a data center, possibly with enhanced security measures or levels.)
data circuit-terminating equipment (DCE) - (A service provider's device, or telecommunications company's device that does the actual data transmission and switching in the frame relay cloud.)
data communication equipment (DCE) - (Generic term for the various devices and equipment involved in providing communication services for a network.)
data control language (DCL) - (Database programming language which defines the internal organization of the database.)
data definition language (DDL) -
Data Encryption Algorithm (DEA) -
Data Encryption Standard (DES) - (Key algorithm used for electronic data encryption developed by IBM in the 1970s. It was found that it could be broken and no longer considered secure.)
Data Execution Prevention (DEP) - (Security feature used in operating systems which limits access to executable code, such as by marking certain memory locations as "off limits." Can be done via hardware (CPU) or software (operating system).)
Data Leak Prevention (DLP) - (Comprises the actions that orginizations take to prevent unauthorized external parties from gaining access to sensitive data. Data Leak Prevention is somewhat different from Data Loss Prevention, which involves measures to prevent the loss or theft of data. Data leak, technically, means that the confidentiality of data has been compromised even if the data is still there, while data loss means that the data is gone or missing.)
Data Loss Prevention (DLP) - (Comprises the actions that orginizations take to prevent the loss, theft, or destruction of data. Data loss can involve situations where data is totally missing from a system or is still there, but cannot be accessed, such as when it has been destroyed, corrupted, or encrypted. Data Loss Prevention is somewhat different from Data Leak Prevention, which involves measures to prevent unauthorized access, use, or disclosure of data. Data leak, technically, means that the confidentiality of data has been compromised even if the data is still there, while data loss means that the data is gone or missing.)
Data Loss Protection (DLP) - (A generic term for any actions that orginizations take to protect system data. It can involve both measures to prevent the loss, theft, or destruction of data (data loss) - situations where data is totally missing from a system or is still there, but cannot be accessed, such as when it has been destroyed, corrupted, or encrypted - as well as measures taken to prevent the compromise of data confidentiality (data leak). Data leak, technically, means that the confidentiality of data has been compromised even if the data is still there, while data loss means that the data is gone or missing.)
data manipulation language (DML) -
Data-Over-Cable Service Interface Specification (DOCSIS) - (data transfer standard)
Data Reference Model (DRM) -
Data Rights Management (DRM) - (Data protection area which involves the use of additional controls beyond normal data security protection measures, such as enhanced access control lists (ACL) imposed on data sets requiring additional permissions or conditions in order to access and use data. DRM serves to control the extent of distribution.)
Database Activity Monitor (DAM) - (A suite of tools that can be used to support the ability to identify and report on fraudulent, illegal, or other undesirable behavior, with minimal impact on user operations and productivity.)
database management system (DBMS) - (Software application, suite of programs, or generally, a method of database management, which involves the storage of data in a database (structured storage mechanism used for organizing and storing large amounts of data), allowing users and applications to access, view, and modify that data as needed. A DBMS usually has capabilities for sorting records, selecting data based on certain criteria, counting the number of records meeting certain criteria, and performing calculations.)
decibel (dB) - (A unit of relative loudness or power. Decibel is used in 3 ways: 1) to express the ratio of 2 power levels; 2) to express the ratio of 2 voltage levels; or 3) to describe the loudness of sound (relative to the threshold of human hearing).)
Deep Packet Inspection engine (DPI) - (Device or software which can conduct extensive analysis of data packets.)
Defense Industrial Base (DIB) - (Manufacturing and production facilities which make up the military production capabilities of a nation.)
Defense Information Systems Agency (DISA) - (Agency within the U.S. Department of Defense (DoD) which provides intelligence and communications services to the various branches of the U.S. military. Originally established as the Defense Communications Agency (DCA) in 1960, it was renamed the Defense Information Systems Agency (DISA) in 1991. While its role would expand beyond active military operations and conflict to include humanitarian assistance and disaster relief and services to non-military agencies, such as the U.S. State Department, it has narrowed its focus to the technological side of intelligence and communications systems, but with enhanced capabilities in cyber security, along with offensive and defensive capabilities in cyber warfare.)
Define, Measure, Analyze, Improve, and Control (DMAIC) - (A management model for information security management systems involving the steps incorporated into, or part of, a continuous improvement process.)
Demilitarized Zone (DMZ) - (A buffer zone or network segment located between a protected network and unprotected networks, such as the Internet. Prevents outside traffic from the Internet from directly accessing a protected network.)
Denial-of-Service Attack (DoS) - (A cyber attack on a network/software which overwhelms or degrades the service or resource, making it unavailable to legitimate users.)
dense wavelength division multiplexing (DWDM) - (High-speed optical network technology which uses multiple light wavelengths on a single fiber, with each wavelength capable of supporting multiple simultaneous transmissions.)
Department of Defense (U.S.) (DoD) - (Cabinet-level department responsible for oversight of all military branches, military preparedness, defense budgets, and military readiness of the various services)
Department of Defense Architecture Framework (DoDAF) - (Standard used by the U.S. military in the acquisition, development, and modification of technology and weapons systems to ensure that different devices and systems communicate using the same protocol types, software components, and data elements.)
Department of Defense Information Assurance Certification and Accreditation Process (DIACAP) - (Certification process, released in 2007, required by the Department of Defense involving an evaluation of the extent to which the security controls implemented for a system meet the system's security requirements. Replaced DITSCAP, which had been released in 1997.)
Department of Defense Information Assurance Risk Management Framework (DIARMF) -
Department of Defense Information Technology Security Certification and Accreditation Process (DITSCAP) - (Certification and accreditation process for military security systems, released in 1997. DITSCAP was replaced by the DIACAP (DoD Information Assurance Certification and Accreditation Process) in 2007.)
Department of Defense Instruction (DoDI) -
Department of Defense Manual (DoDM) -
Department of Homeland Security (DHS) - (Cabinet-level agency created by the Homeland Security Act of 2002 in November 2002, intended to oversee and coordinate security efforts related to terrorism and threats against the United States. All or portions of 22 federal agencies, such as the Coast Guard, the Customs Service, and Secret Service were merged or transferred into DHS)
Department of Motor Vehicles (DMV) - (State agencies which oversee the regulation of driving and drivers within their state, set standards for driving privileges, issue or revoke driver's licenses, and maintain records of those issued licenses.)
Design Basis Threat (DBT) - (Term used in the context of nuclear facilities. A description of the attributes and characteristics of potential insider and/or external adversaries who might attempt unauthorized removal of nuclear material or engage in sabotage. This type of threat serves as the criteria against which physical protection systems are evaluated, even in the design phase.)
Development and Operations (DevOps) - (A software engineering culture and practice that aims to unify software development (Dev) and software operations (Ops). The main characteristic of the DevOps movement is to advocate automation and monitoring at all steps of software construction, from integration, testing, and releasing, to deployment and infrastructure management.)
Development Security Operations (DevSecOps) - (A software engineering culture and practice that incorporates security (Sec) into software development (Dev) and software operations (Ops) and which strives to automate core security tasks by embedding security controls and processes into the DevOps workflow. )
device identifier (DevID) -
dial-on-demand routing (DDR) -
Dial-Up Networking (DUN) -
digital-to-analog converter (DAC (D/A converter)) - (An electronic circuit that coverts digital information (binary numbers) into voltages at specific levels.)
digital-to-audio conversion (DAC) - (Process of converting digital information (binary numbers) into sounds (waveform audio).)
digital audio extraction (DAE) - (Process in which digital audio data is read directly from a disc and passed directly in its raw digital form to the PC's processor, rather than being converted to an analog format.)
Digital Display Working Group (DDWG) -
Digital Encryption Standard (DES) -
Digital Equipment Corporation (DEC) -
Digital Forensic Research Workshop (DFRWS) -
Digital Light Processing (DLP) -
digital micromirror device (DMD) -
Digital Millennium Copyright Act (DMCA) - (legal)
digital multimeter (DMM) - (tester)
Digital Object Identifier (DOI) -
Digital Research - Disk Operating System (DR-DOS) -
Digital Rights Management (DRM) - (Technological measures and tools that businesses use to protect their content, such as software access controls used in the entertainment industry to prevent unauthorized copying of copyrighted videos or movies.)
digital signal processing (DSP) -
digital signal processor (DSP) -
Digital Signature Algorithm (DSA) -
Digital Signature Standard (DSS) - (A standard for digital signatures (which are hash values encrypted with the sender's private key), requiring the use of a special digital signature algorithm.)
Digital Subscriber Line (DSL) - (A group of technologies that provide high-speed data transmission over existing telephone wiring.)
digital subscriber line access multiplexer (DSLAM) -
digital television (DTV) -
digital versatile disc (DVD) - (An optical disc, similar to CD-ROM, but with much greater capacity.)
digital versatile disc - random access memory (DVD-RAM) -
digital versatile disc - read only memory (DVD-ROM) -
digital versatile disc - recordable (DVD-R) -
digital versatile disc - rewritable (DVD-RW) -
digital video disc (DVD) - (original name for a digital versatile disc.)
Digital Video Express (DIVX) - (discontinued)
Digital Video Interface (DVI) -
digital video recorder (DVR) -
Digital Visual Interface (DVI) -
direct access storage device (DASD) - (General term for magnetic disk storage devices, which historically have been used in mainframe and minicomputer (mid-range computer) environments. Direct access is a capability which allows data to be directly accessed, in contrast to sequential access, which requires going through all data locations to reach the desired data, such as in tape storage.)
direct(ly) attached storage (DAS) - (Disk drives or other storage devices that are connected directly to the computer that uses them, rather than connected through a network.)
direct current (DC) - (An electric current of constant direction, having a magnitude that does not vary or varies only slightly, in contrast to alternating current, an electrical current that reverses direction at regular intervals. Alternating current is created when a wire, made of conductive material, such as metal, moves through a magnetic field.)
direct inward dialed (DID) - (phone)
direct inward system access (DISA) - (phone)
Direct Media Interface (DMI) -
direct memory access (DMA) - (Devices which allow access directly to computer memory.)
Direct Memory Addressing (DMA) -
direct sequence spread spectrum (DSSS) - (wireless transmission)
directory (dir) - (Windows command line)
disaster recovery (DR) - (The process of reacting to an incident or disaster and recovering an organization, its personnel, and its systems to a functioning state.)
Disaster-Recovery-as-a-Service (DRaaS) - (A cloud-based computing service used for data and system recovery in the event of a disaster.)
Disaster Recovery Plan (DRP) - (A plan to recover organizational operations after a disaster hits. Ideally, will involve a written plan involving an inventory of assets, including employees, an identification of priorities and staffing needs, chain of command, delegation of authority, short-term emergency procedures, and steps to taken to restore operations.)
Disaster Recovery Planning (DRP) - (The process of planning for recovery from disasters, including the development of a plan, budgeting, implementation, and taking steps toward recovery rediness.)
Discover, Offer, Request, and Acknowledgment (D-O-R-A) - (address assignment process)
Discrete Multitone (DMT) -
discretionary access control (DAC) - (Access to a resource (file or folder) which can be granted or denied, at the discretion of the "owner" of that resource. This model is based on the idea that there is an owner of a resource, such as a file, who has the authority to decide who has access. In the case of an individual, the creator of a file or folder, is considered to be the owner. At the departmental level, the department manager, or business unit manager, can be assigned ownership, with the authority to grant or deny access and at what level. Access can also be restricted in varying degrees, such as permission to add, change, or edit files, or restricted to "view only," which allows a user to view data, such as customer accounts but is not allowed to make changes.)
Disk at once (DAO) - (A single-session method of writing CDs in which the lead-in (start labeling/marking indicator), data tracks, and lead-out are written in a single operation without the writing laser ever turning off; then the disc is closed.)
Disk Operating System (DOS) -
Disk Operating System Protected Mode Interface (DPMI) -
Display Data Channel (DDC) -
Display Power-Management Signaling (DPMS) -
distinguished names (DNs) - (database organization)
Distributed Component Object Model (DCOM) -
Distributed Computing Environment (DCE) - (A standard developed by the Open Software Foundation (OSF) providing a client/server framework that is available to many vendors to use within their products. DCE is a set of management services, such as security, directory, time, and distributed file support.)
distributed control system (DCS) -
Distributed Denial of Service Attack (DDoS) - (A denial of service attack that uses a number of systems or hosts from around the world, or various geographic locations, to flood and overwhelm a network, in order to make a server or system unavailable.)
Distributed Denial of Service-as-a-Service (DDoSaaS) - (An online software package sold in underground markets and/or forums using a subscription-based model, created by malware authors who develop malicious code, package it as an online dashboard, complete with instructions, allowing for individual modification, and presented for sale or rent. Can come in a variety of forms, depending on the type or method of attack promoted, such as ransomware, promoted as Ransomware-as-a-Service (RaaS), or denial-of-service attacks.)
Distributed Internet Architecture (DNA) - (Windows)
Distributed/Distribution Management System (DMS) - (Term for Distributed Control Systems (DCS) or Industrial Control Systems (ICS) used by utilities or other industrial systems involving geographically dispersed networks of control devices which operate semi-independently but are part of larger network operations systems.)
Distributed Network Protocol 3 (DNP3) -
Document Object Model (DOM) -
Document Object Model Cross-Site Scripting Attack (DOM XSS) -
document type definition (DTD) -
domain component (dc) - (In a Windows environment, a method of naming, or identifying, individual commponents of a database, which is managed by a domain controller (DC).)
domain controller (DC) - (In a Windows environment, a component or function, which runs the Active Directory directory service, by organizing network resources and making those resources available to users.)
Domain Name Server (DNS) -
Domain Name Service (DNS) - (Sometimes referred to as Domain Name System.) (The service and protocol associated with resolving Internet Protocol (IP) addresses (typically written in dotted-decimal notation form - 10.3.2.1 or 12.56.42.34) to human-recognizable domain names - www.website.com)
Domain Name/Naming System (DNS) - (Sometimes referred to as Domain Name Service.) (The service and protocol associated with resolving Internet Protocol (IP) addresses (typically written in dotted-decimal notation form - 10.3.2.1 or 12.56.42.34) to human-recognizable domain names - www.website.com)
Domain Name System Blacklist (DNSBL) - (System setup which blocks e-mails from listed domain names.)
Domain Name Service/System Security (DNSSEC) - (Authentication mechanism which validates the origin of a message to ensure that it is not spoofed and potentially malicious using a combination of PKI (Public Key Infrastructure) - a framework of programs, procedures, communication protocols, and public key cryptography that enables a diverse group of individuals to communicat securely - and digital signatures - hash values encrpted with the sender's private key.)
Domain Name System Security Extensions (DNSSEC) - (Type of secure protocol used to protect DNS (Domain Name System) operations when Internet names are being resolved with IP addresses.)
dots per inch (dpi) -
double data rate (DDR) -
Double Data Rate Synchronous Dynamic Random Access Memory (DDR SDRAM) -
double-layer (DL) - (DVD)
Draft Standard (DS) -
drive active/slave present (DASP) - (Type of Parallel Advanced Technology Attachment (PATA) signal during power-on initialization which indicates whether a slave (dependent or controlled component) drive is present on the interface.)
Drug Enforcement Agency (DEA) - (U.S. federal agency dealing with enforcement of drug laws.)
dual-attached concentrator (DAC) - (A type of high-speed fiber distributed data interfac (FDDI) technology concentrator (physical communication device allowing several computers and devices to communicate with each other - also known as a hub) which connects devices to both a primary and secondary ring.)
dual-attachment station (DAS) - (Device with two ports, with each port capable of providing a connection for both the primary and the secondary rings. The dual-attachment station (DAS) is one category of Fiber Distributed Data Interface (FDDI) technology which is a high-speed, token-passing ring involving 2 rings, a primary and a secondary (or backup) ring. FDDI is often used in metropolitan area networks (MANs) because of its suitability for moderate distance transmission/communication.)
Dual Independent Bus (DIB) - (architecture)
dual inline memory module (DIMM) -
dual inline package (DIP) - (chip)
dual-tone multi-frequency (DTMF) -
Dvorak Simplified Keyboard (DSK) -
dynamic access policies (DAP) - (Security controls that ensure that systms are running and up-to-date, or that antivirus software is current and running.)
Dynamic Application Security Testing (DAST) - (A process of testing an application or software product in an operating state, i.e., while it is running.)
dynamic bass boost (DBB) - (Computer speaker function which provides a more powerful bass and clearer treble, regardless of the volume setting.)
Dynamic Domain Name System (DDNS) (DynDNS) - (A service or software which monitors the IP address of a device referenced in the Domain Name System (DNS) record, and looks for changes, such as when a device obtains a new IP address from a service provider, in order to update the IP address.)
Dynamic Host Configuration Protocol (DHCP) - (A method to dynamically assign IP addresses to network devices. It can also assign other IP parameters, such as subnet masks or the IP address of a DNS server.)
Dynamic Link Library (DLL) - (A module that contains functions (called exported functions or exports) that can be used by another program.)
Dynamic Network Address Translation (DNAT) - (Form of Network Address Translation (NAT) process where inside local addresses are automatically (dynamically) assigned an inside global address from a pool of available addresses.)
Dynamic Optimization (DO) - (The process of moving and reallocating virtual machines and resources within a cluster environment to maintain optimal performance with balanced and distributed resource utilization.)
Dynamic Random Access Memory (DRAM) -
Dynamic Video Memory Technology (DVMT) -
Dynamically-Generated Algorithm (DGA) - (Type of cyber attack in which attackers generate new command and control (C&C) hosts with seemingly random domain names, which overcome "block" lists (lists of hosts which are to be blocked) since the new names are not already classified or listed by security systems.)
Triple Data Encryption Standard (3DES) - (Variation of Data Encryption Standard (DES) which uses three rounds of DES encryption. DES was no longer considered secure.)