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D
daemon
A networking program, usually associated with UNIX systems, that runs in the background performing tool functions such as housekeeping or maintenance without user intervention or awareness. Pronounced "demon."
Data Encryption Standard (DES)
An encryption algorithm that uses a 56-bit key and maps a 64-bit input block to a 64-bit output block. The key appears to be a 64-bit key, but one bit in each of the eight bytes is used for odd parity, resulting in 56 bits of usable key.See also key.
data source tier
A logical layer that represents a computer running a Database Management System (DBMS), such as a SQL Server database.See also client tier.See also middle tier.
datagram
One packet, or unit, of information that includes relevant delivery information, such as the destination address, that is sent through a packet-switching network.See also packet.
DCOM
See Distributed Component Object Model (DCOM).
deadlock
A situation in which a thread will not relinquish its exclusive access to a critical section.
debugger
A program designed to aid in detecting, locating, and correcting errors in another program by allowing the programmer to step through the program, examine the data, and monitor conditions such as the values of variables.
decryption
The process of making encrypted data readable again by converting ciphertext to plaintext.See also encryption.See also plaintext.
default document
The file that is sent by a Web server when it receives a request for a Uniform Resource Locator (URL) that does not specify a file name. This document can be generated automatically by the server, or it can be a custom file that is placed in that directory by the administrator. Sometimes called a default home page.
default gateway
A configuration item for the TCP/IP protocol that is the IP address of a directly reachable IP router. Configuring a default gateway creates a default route in the IP routing table.See also Internet Protocol (IP).See also IP address.See also Transmission Control Protocol/Internet Protocol (TCP/IP).
DES
See Data Encryption Standard (DES).
details pane
The right pane in Microsoft Management Console (MMC) that displays details for the selected item in the console tree. The details can be a list of items or they can be administrative properties, services, and events that are acted on by a snap-in.See also console tree.See also snap-in.
DHCP
See Dynamic Host Configuration Protocol (DHCP).
dial-up connection
The connection to your network if you use a device that uses the telephone network. This includes modems with a standard telephone line, ISDN cards with highspeed ISDN lines, or X.25 networks.If you are a typical user, you might have one or two dial-up connections, for example, to the Internet and to your corporate network. In a more complex server situation, multiple network modem connections might be used to implement advanced routing.See also Integrated Services Digital Network (ISDN).See also modem(modulator/demodulator).
dial-up networking (DUN)
Connecting to a remote network or the Internet through a dial-up connection, such as a modem.
Digest authentication
An authentication mechanism that hashes user name, password, and other data before transmitting it over the network.See also authentication.See also Basic authentication.See also encryption.See also hash.
digital certificate
An electronic certification issued by certification authorities that shows where a program comes from and proves that the installation package has not been altered. Administrators should sign their code with a digital certificate if planning to distribute an Internet Explorer package over the Internet.See also certification authority (CA).
digital signature
The part of a digital certificate that contains an encryption key that uniquely identifies the holder of the certificate.See also certificate.See also client.See also key pair.
directory
An information source that contains information about users, computer files, or other objects. In a file system, a directory stores information about files. In a distributed computing environment (such as a Windows domain), the directory stores information about objects such as printers, fax servers, applications, databases, and other users.See also object.
directory browsing
A feature that automatically provides a default Web page of available directories and files to browsers that submit a Uniform Resource Locator (URL) that does not specify a particular file.
directory partition
A contiguous subtree of Active Directory that is replicated as a unit to other domain controllers in the forest that contain a replica of the same subtree. In Active Directory, a single domain controller always holds at least three directory partitions: schema (class and attribute definitions for the directory), configuration (replication topology and related metadata), and domain (subtree that contains the per-domain objects for one domain). Domain controllers running Windows Server 2003 can also store one or more application directory partitions.See also Active Directory.See also attribute.See also domain.
directory replication
The copying of a master set of directories from a server (called an export server) to specified servers or workstations (called import computers) in the same or other domains. Replication simplifies the task of maintaining identical sets of directories and files on multiple computers because only a single master copy of the data must be maintained. Files are replicated when they are added to an exported directory and every time a change is saved to the file.
directory service
Both the directory information source and the service that makes the information available and usable. A directory service enables the user to find an object when given any one of its attributes.See also Active Directory.See also attribute.See also object.
Distributed Component Object Model (DCOM)
The Microsoft Component Object Model (COM) specification that defines how components communicate over Windows-based networks. Use the DCOM Configuration tool to integrate client/server applications across multiple computers. DCOM can also be used to integrate robust Web browser applications.See also Component Object Model (COM).
distributed processing
A computing environment that contains a client and a server. This structure allows the workload to be divided into parts yet appear as a single process.
DLL
See dynamic-link library (DLL).
DNS
See Domain Name System (DNS).
domain
In Active Directory, a collection of computer, user, and group objects defined by the administrator. These objects share a common directory database, security policies, and security relationships with other domains.In DNS, any tree or subtree within the DNS namespace. Although the names for DNS domains often correspond to Active Directory domains, DNS domains should not be confused with Active Directory domains.See also Active Directory.See also object.
domain controller
In an Active Directory forest, a server that contains a writable copy of the Active Directory database, participates in Active Directory replication, and controls access to network resources. Administrators can manage user accounts, network access, shared resources, site topology, and other directory objects from any domain controller in the forest.See also Active Directory.See also authentication.See also forest.See also shared resource.
domain name
The name given by an administrator to a collection of networked computers that share a common directory. Part of the DNS naming structure, domain names consist of a sequence of name labels separated by periods.See also domain.See also Domain Name System (DNS).
Domain Name System (DNS)
A hierarchical, distributed database that contains mappings of DNS domain names to various types of data, such as IP addresses. DNS enables the location of computers and services by user-friendly names, and it also enables the discovery of other information stored in the database.See also IP address.See also ping.See also Transmission Control Protocol/Internet Protocol (TCP/IP).
DWORD
A data type that is composed of hexadecimal data with a maximum allotted space of 4 bytes.
dynamic binding
Binding (converting symbolic addresses in the program to storage-related addresses) that occurs during program execution. The term often refers to object-oriented applications that determine, during run time, which software routines to call for particular data objects. Also called late binding.
Dynamic Host Configuration Protocol (DHCP)
A TCP/IP service protocol that offers dynamic leased configuration of host IP addresses and distributes other configuration parameters to eligible network clients. DHCP provides safe, reliable, and simple TCP/IP network configuration, prevents address conflicts, and helps conserve the use of client IP addresses on the network.DHCP uses a client/server model where the DHCP server maintains centralized management of IP addresses that are used on the network. DHCP-supporting clients can then request and obtain lease of an IP address from a DHCP server as part of their network boot process.See also IP address.See also Transmission Control Protocol/Internet Protocol (TCP/IP).
Dynamic HTML
A collection of features that extends the capabilities of traditional HTML, giving Web authors more flexibility, design options, and creative control over the appearance and behavior of Web pages.
dynamic page
A Hypertext Markup Language (HTML) document that contains animated GIFs, Java applets, ActiveX Controls, or dynamic HTML (DHTML). Also, a Web page that is created automatically, based on information that is provided by the user, or that is generated "on the fly" with Active Server Pages (ASP).
dynamic-link library (DLL)
An operating system feature that allows executable routines (generally serving a specific function or set of functions) to be stored separately as files with .dll extensions. These routines are loaded only when needed by the program that calls them.
