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  • Daemon
    A persistent process that services requests as they arrive, without human intervention. Server processes, such as those for HTTP and FTP, run as daemons.
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  • DAML
    DARPA Agent Markup Language. A language currently in development for presenting information on the World Wide Web that will allow information objects to be tagged in a way that allows software applications, computer agents, and virtual assistants to recognize both specific meaning as well as relationships among the information objects.
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  • Data
    Information in its raw form. The characters, numbers, pixels, bits and bytes that make up digitized information.
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  • Data center
    A facility used to house mission critical computer systems and associated components. They generally include environmental controls (air conditioning, fire suppression, etc.), redundant/backup power supplies, and high security. Internet Service and Web Hosting Providers generally locate their Points of Presence and Web server facilities in data centers.
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  • Data Encryption Standard (DES)
    A secret key-based cryptosystem. To use DES for communication, both the sender and the receiver must know the same secret key, which is used to provide both encryption and decryption of the message. DES is the most well known and widely used cryptographic system in the world. It was originally developed by IBM and was endorsed by the U.S. government in 1977 as an official standard.
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  • Data mining
    The process of identifying and extracting patterns from data, particularly from very large and/or complex sets of data.
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  • Debit card
    A payment card used to make purchases or to obtain cash. The amount of a debit card purchase or withdrawal is debited from the cardholder's account immediately. Contrast with credit card and charge card.
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  • Decryption
    Translation of ciphertext into plaintext.
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  • Dedicated hosting
    A form of Web hosting where the hosting provider dedicates a single machine for a customer's Web site(s).
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  • Desktop
    The background behind open computer windows, menus, and dialog boxes: your virtual desk. The look of your desktop can be changed by applying different properties to it through the control panel.
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  • Dial-up
    Access to the Internet via a modem and telephone line, which requires that the computer dial a phone number for access. Contrast with leased line.
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  • Digital
    The representation of analog information as ones and zeros.
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  • Digital certificate
    An electronic document, signed with a digital signature, that attests to the ownership of something; especially a certificate signed by a certification authority who attests to the ownership of a public key by an individual or an organization. X.509 is an international standard that defines a framework for authentication services and specifies formats for public key certificates.
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  • Digital signature
    A value computed with a cryptographic algorithm and appended to data in such a way that any recipient of the data can use the signature to verify the data's origin and integrity. The electronic counterpart of a handwritten signature on a hard copy document.
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  • Directed dialog
    A speech-enabled application in which the computer prompts the user for each input in a specific order. The user must respond with one of a small number of responses.
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  • Discrete speech recognition
    A voice input system in which the speaker must pause between words, usually between 1/10th and 2/10ths second, for the computer to determine where words begin and end.
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  • Discussion group
    A general term for an online "bulletin board" where you can leave messages and see responses to messages you have left. Discussion groups generally keep a history of comments made, and often support attachments for messages.
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  • Disruption tolerant network
    A network designed so that temporary or intermittent communications obstacles do not completely stop the flow of message traffic. In a disruption tolerant network, data continues to advance toward its destination despite broken links or other obstacles.
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  • Document
    An attachment or file.
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  • Domain document retrieval
    See information retrieval. An Internet domain refers to a networked computer accessible through a host, or domain, name. A domain identity includes a distinguishing suffix. Some important domains suffixes are: .com (commercial), .edu (educational, primarily in the U.S.), .net (network operations), .gov (U.S. government), and .mil (US military). Most countries also have a domain. For example, .us (United States), .uk (United Kingdom), .au (Australia). Within the .us domain, there are subdomains for the fifty states, each generally with a name identical to the state's postal abbreviation. Within the .uk domain, there is a .ac.uk subdomain for academic sites and a .co.uk domain for commercial sites.
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  • Domain name
    A name for a computer that distinguishes it from all other computers on an internet (such as the Internet or another IP-based network such as an intranet). This name is mapped by DNS to a unique IP address. Example: www.openmarket.com. (The term 'hostname' has grown to be synonymous with this definition of 'domain name'.)
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  • DNS
    Domain Name System. When you send e-mail or point a browser to an Internet domain such as cnet.com, the domain name system translates the names into Internet addresses (a series of numbers looking something like this: 123.123.23.2). The term refers to two things: the conventions for naming hosts and the way the names are handled across the Internet.
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  • Download
    To obtain a data file or digital good by transmission over a network, typically by following a URL, or using FTP.
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  • DSU (digital service unit)
    Connects a CSU to data terminal equipment. Handles transmission (including formatting) of data over medium to high-speed digital communication circuits.
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  • Dynamic
    Constantly changing, or generated on-demand. For example, dynamic Web pages are custom generated (generally through a database query) based on a set of parameters supplied by the browser or the end user.
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  • Dynamic Spectrum Access
    A decentralized approach to spectrum allocation that allows a communication device, such as a mobile phone or radio, to operate on any unused, available spectrum.
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