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D
D-channel
A separate channel of an
ISDN line that is used for ISDN signaling. For ISDN Basic Rate Interface
(BRI), the D-channel is 16 kilobits per second (Kbps). For ISDN Primary
Rate Interface (PRI), the D-channel is 64 Kbps. D-channel is also called
data channel.
daily
backup
A backup that copies all
selected files that have been modified the day the daily backup is
performed. The backed-up files are not marked as having been backed up (in
other words, the archive attribute is not cleared).
Data Communications Equipment
(DCE)
One of two types of
hardware connected by an RS-232-C serial connection, the other being a
Data Terminal Equipment (DTE) device. A DCE is an intermediary device that
often transforms input from a DTE before sending it to a recipient. A
modem, for example, is a DCE that modulates data from a microcomputer
(DTE) and sends it along a telephone connection.
Data Link Control
(DLC)
An address that uniquely
identifies a node on a network. Every network adapter has a DLC address or
DLC identifier (DLCI). Some network protocols, such as Ethernet and Token
Ring, use DLC addresses exclusively. Other protocols, such as TCP/IP, use
a logical address at the OSI Network layer to identify nodes.
However, all network
addresses must eventually be translated to DLC addresses. In TCP/IP
networks, this translation is performed by the Address Resolution Protocol
(ARP).
data
packet
A unit of information
transmitted as a whole from one device to another on a network.
Data Terminal Equipment
(DTE)
In the RS-232-C hardware
standard, any device, such as a remote access server or client, that has
the ability to transmit information in digital form over a cable or a
communications line.
data-overrun
error
A state in which the
sending computer is transmitting characters faster than the receiving
computer can accommodate them. If this problem persists, reduce the
bits-per-second (bps) rate.
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.
dead-letter
queue
For Message Queuing, a
queue that stores nontransactional messages that are undeliverable or
expired. These queues store failed messages on the computer on which the
message expired. Messages in these queues are written to disk and are
therefore recoverable.
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.
dedicated
adapter
The network adapter that,
when using multiple network adapters in each host of a Network Load
Balancing cluster, handles network traffic not related to cluster
operations (the traffic for individual hosts on the network). This adapter
is programmed with the host's dedicated IP address.
default
button
In some dialog boxes, the
command button that is selected or highlighted when the dialog box is
initially displayed. The default button has a bold border, indicating that
it will be chosen automatically if you press ENTER. You can override a
default button by clicking Cancel or another command
button.
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.
default
host
The host with the highest
host priority for which a drainstop command is not in progress.
After convergence, the default host handles all of the network traffic for
TCP and UDP ports that are not otherwise covered by port
rules.
default
network
In the Macintosh
environment, the physical network on which the processes of a server
reside as nodes and on which the server appears to users. The default
network of the server must be one to which that server is attached. Only
servers on AppleTalk Phase 2 internets have default
networks.
default
printer
The printer to which a
computer sends documents if you select the Print command without
first specifying which printer you want to use with a program. You can
have only one default printer; it should be the printer you use most
often.
default
user
The profile that serves
as a basis for all user profiles. Every user profile begins as a copy of
the default user profile.
default
zone
The zone to which all
Macintosh clients on the network are assigned by
default.
defragmentation
The process of rewriting
parts of a file to contiguous sectors on a hard disk to increase the speed
of access and retrieval. When files are updated, the computer tends to
save these updates on the largest continuous space on the hard disk, which
is often on a different sector than the other parts of the file. When
files are thus fragmented, the computer must search the hard disk each
time the file is opened to find all of the file's parts, which slows down
response time.
delegation
The ability to assign
responsibility for management and administration of a portion of the
namespace to another user, group, or organization.
For DNS, a name service
record in the parent zone that lists the name server authoritative for the
delegated zone.
denial-of-service
attack
An attack in which an
attacker exploits a weakness or a design limitation of a network service
to overload or halt the service, so that the service is not available for
use. This type of attack is typically launched to prevent other users from
using a network service such as a Web server or a file
server.
dependency
A relationship of
reliance between two resources that makes it necessary for them to run in
the same group on the same node. For example, an application is dependent
on the disks that contain its data resources.
dependency
tree
A diagram for visualizing
the dependency relationships between resources.
dependent
client
For Message Queuing, a
computer that requires synchronous access to a Message Queuing server to
perform all standard message queuing operations, such as sending and
receiving messages and creating queues.
descendent
key
All the subkeys that
appear when a key in the registry is expanded. A descendent key is the
same as a subkey.
desired
zone
The zone in which
AppleTalk network integration appears on the
network.
desktop
The on-screen work area
on which windows, icons, menus, and dialog boxes
appear.
desktop
pattern
A design that appears
across your desktop. You can create your own pattern or select a pattern
provided by Windows.
destination
document
The document into which a
package or a linked or embedded object is being inserted. For an embedded
object, this is sometimes also called the container
document.
details
pane
The pane in the Microsoft
Management Console (MMC) that displays the 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.
device
Any piece of equipment
that can be attached to a network or computer; for example, a computer,
printer, joystick, adapter, or modem card, or any other peripheral
equipment. Devices normally require a device driver to function with
Windows.
device
conflict
A conflict that occurs
when the same system resources have been allocated to two or more devices.
System resources include interrupt request (IRQ) lines, direct memory
access (DMA) channels, input/output (I/O) ports, and memory
addresses.
device
driver
A program that allows a
specific device, such as a modem, network adapter, or printer, to
communicate with the operating system. Although a device might be
installed on your system, Windows cannot use the device until you have
installed and configured the appropriate driver.
If a device is listed in
the Hardware Compatibility List (HCL), a driver is usually included with
Windows. Device drivers load automatically (for all enabled devices) when
a computer is started, and thereafter run invisibly.
device
fonts
Fonts that reside in your
printer. They can be built into the printer itself or provided by a font
cartridge or font card.
Device
Manager
An administrative tool
that you can use to manage the devices on your computer. Using Device
Manager, you can view and change device properties, update device drivers,
configure device settings, and uninstall devices.
DFS link
An element in the
Distributed File System (DFS) namespace that lies below the root and maps
to one or more targets, each of which corresponds to a shared folder or
another DFS root.
DFS root
The starting point of the
Distributed File System (DFS) namespace. The root is often used to refer
to the namespace as a whole. A root maps to one or more root targets, each
of which corresponds to a shared folder on a server.
DFS
topology
The overall logical
hierarchy of the Distributed File System (DFS), including elements such as
roots, links, shared folders, and replica sets, as depicted in the DFS
administrative console. This is not to be confused with the DFS namespace,
which is the logical view of shared resources seen by
users.
DHCP
client
Any network-enabled
device that supports the ability to communicate with a DHCP server for the
purpose of obtaining dynamic leased IP configuration and related optional
parameters information.
DHCP
option
Address configuration
parameters that a DHCP service assigns to clients. Most DHCP options are
predefined, based on optional parameters defined in Request for Comments
(RFC) 1542, although extended options can be added by vendors or
users.
DHCP
server
A computer running the
Microsoft DHCP service that offers dynamic configuration of IP addresses
and related information to DHCP-enabled clients.
DHCP service
resource
A resource type that
provides DHCP services from a cluster.
DHCP/BOOTP Relay
Agent
The agent program or
component responsible for relaying DHCP and BOOTP broadcast messages
between a DHCP server and a client across an IP router. A DHCP relay agent
supports DHCP/BOOTP message relay as defined in RFCs 1541 and 2131. The
DHCP Relay Agent service is managed using the Routing and Remote Access
service.
dial
location
The country code, area
code, and specific dialing requirements for the place you are dialing
from. Once you have created a dial location, you can select it to apply
the dialing requirements to all your calls. To change dialing locations,
select or create a different one.
dial-up
connection
The connection to your
network if you are using a device that uses the telephone network. This
includes modems with a standard phone line, ISDN cards with high-speed
ISDN lines, or X.25 networks.
If you are a typical
user, you may 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.
dialog box
A secondary window that
contains buttons and various kinds of options through which you can carry
out a particular command or task.
dictionary
attack
A method of guessing a
user's password or PIN by trying every word in the dictionary until
successful.
differential
backup
A backup that copies
files created or changed since the last normal or incremental backup. It
does not mark files as having been backed up (in other words, the archive
attribute is not cleared). If you are performing a combination of normal
and differential backups, restoring files and folders requires that you
have the last normal as well as the last differential
backup.
differential
data
Saved copies of changed
data that can be applied to an original volume to generate a volume shadow
copy.
digital
signature
A means for originators
of a message, file, or other digitally encoded information to bind their
identity to the information. The process of digitally signing information
entails transforming the information, as well as some secret information
held by the sender, into a tag called a signature. Digital signatures are
used in public key environments, and they provide nonrepudiation and
integrity services.
Digital Signature Standard
(DSS)
A standard that uses the
Digital Signature Algorithm (DSA) for its signature algorithm and SHA-1 as
its message hash algorithm. DSA is a public-key cipher that is used only
to generate digital signatures and cannot be used for data
encryption.
Digital Subscriber Line
(DSL)
A type of high-speed
Internet connection using standard telephone wires. This is also referred
to as a broadband connection.
digital video disc
(DVD)
A type of optical disc
storage technology. A digital video disc (DVD) looks like a CD-ROM disc,
but it can store greater amounts of data. DVDs are often used to store
full-length movies and other multimedia content that requires large
amounts of storage space.
direct cable
connection
A link between the I/O
ports of two computers created with a single cable rather than a modem or
other interfacing devices. In most cases, a direct cable connection is
made with a null modem cable.
direct memory access
(DMA)
Memory access that does
not involve the microprocessor. DMA is frequently used for data transfer
directly between memory and a peripheral device such as a disk
drive.
directory
partition
A contiguous subtree of
the directory that forms a unit of replication. A given replica is always
a replica of some directory partition. The directory always has at least
three directory partitions:
·
The schema, which defines the object
classes and attributes contained in Active Directory.
·
The configuration, which identifies
the domain controllers, replication topology and other related information
about the domain controllers within a specific implementation of Active
Directory.
·
One or more domains that contain the
actual directory object data.
A domain controller
always stores the partitions for the schema, configuration, and its own
(and no other) domain. The schema and configuration are replicated to
every domain controller in the domain tree or forest. The domain is
replicated only to domain controllers for that domain. A subset of the
attributes for all domain objects is replicated to the global
catalog.
directory
service
Both the directory
information source and the service that make the information available and
usable. A directory service enables the user to find an object given any
one of its attributes.
DirectX
An extension of the
Microsoft Windows operating system. DirectX technology helps games and
other programs use the advanced multimedia capabilites of your
hardware.
disable
To make a device
nonfunctional. For example, if you disable a device in a hardware
configuration, you cannot use the device when your computer uses that
hardware configuration. Disabling a device frees the resources that were
allocated to the device.
discretionary access control list
(DACL)
The part of an object's
security descriptor that grants or denies specific users and groups
permission to access the object. Only the owner of an object can change
permissions granted or denied in a DACL; thus, access to the object is at
the owner's discretion.
disk
A storage device that is
attached to a computer.
disk configuration
information
Information in the
Windows registry on assigned drive letters, simple volumes, striped
volumes, mirrored volumes, spanned volumes, and RAID-5 volumes. You can
change the disk configuration by using Disk
Management.
dismount
To remove a removable
tape or disc from a drive.
display
adapter
distinguished
name
A name that uniquely
identifies an object by using the relative distinguished name for the
object, plus the names of container objects and domains that contain the
object. The distinguished name identifies the object as well as its
location in a tree. Every object in Active Directory has a distinguished
name. A typical distinguished name might be
CN=MyName,CN=Users,DC=Microsoft,DC=Com
This identifies the
MyName user object in the microsoft.com domain.
distribution
group
A group that is used
solely for e-mail distribution and that is not security-enabled.
Distribution groups cannot be listed in discretionary access control lists
(DACLs) used to define permissions on resources and objects. Distribution
groups can be used only with e-mail applications (such as Microsoft
Exchange) to send e-mail to collections of users. If you do not need a
group for security purposes, create a distribution group instead of a
security group.
DLL
DNS
DNS Server
A service that maintains
information about a portion of the Domain Name System (DNS) database and
responds to and resolves DNS queries. A computer running this service is
also known as a DNS server.
DNS suffix
For DNS, a character
string that represents a domain name. The DNS suffix shows where a host is
located relative to the DNS root, specifying a host’s location in the DNS
hierarchy. Usually, DNS suffix describes the latter portion of a DNS name,
following one or more of the first labels of a DNS
name.
dock
To connect a laptop or
notebook computer to a docking station.
docking
station
A unit for housing a
portable computer that contains a power connection, expansion slots, and
connections to peripherals, such as a monitor, printer, full-sized
keyboard, and mouse. The docking station turns the portable computer into
a desktop computer.
document
Any self-contained piece
of work created with an application program and, if saved on disk, given a
unique file name by which it can be retrieved.
domain
A group of computers that
are part of a network and share a common directory database. A domain is
administered as a unit with common rules and procedures. Each domain has a
unique name.
An Active Directory
domain is a collection of computers defined by the administrator of a
Windows network. These computers share a common directory database,
security policies, and security relationships with other domains. An
Active Directory domain provides access to the centralized user accounts
and group accounts maintained by the domain administrator. An Active
Directory forest is made up of one or more domains, each of which can span
more than one physical location.
A DNS domain is 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.
domain
controller
In a Windows domain
environment, a computer running Active Directory that manages user access
to a network, which includes logging on, authentication, and access to the
directory and shared resources.
domain controller locator
(Locator)
An algorithm that runs in
the context of the Net Logon service and that finds domain controllers on
a Windows 2000 network. Locator can find domain controllers by using DNS
names (for IP/DNS-compatible computers) or by using NetBIOS names (for
computers that are running Windows 3.x, Windows for Workgroups, Windows NT
3.5 or later, Windows 95, or Windows 98, or it can be used on a network
where IP transport is not available).
domain DFS
An implementation of DFS
in which DFS topological information is stored in Active Directory.
Because this information is made available on multiple domain controllers
in the domain, domain DFS provides fault-tolerance for any distributed
file system in the domain.
domain local
group
A security or
distribution group that can contain universal groups, global groups, and
accounts from any domain in the domain tree or forest. A domain local
group can also contain other domain local groups from its own domain.
Rights and permissions can be assigned only at the domain containing the
group.
domain
name
The name given by an
administrator to a collection of networked computers that share a common
directory. Part of the Domain Name System (DNS) naming structure, domain
names consist of a sequence of name labels separated by
periods.
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.
domain
namespace
The database structure
used by the Domain Name System (DNS).
domain naming
master
The domain controller
assigned to control the addition or removal of domains in the forest. At
any time, there can be only one domain naming master in the
forest.
domain of
origin
The parent DNS domain
name that is used to root either a zone or a resource record within a
zone. This name is joined to the end of unqualified or relative domain
names to form a fully qualified domain name (FQDN) within the zone. In DNS
Manager, the domain of origin will correspond to Zone name as it
appears in the Add Zone Wizard or the name that appears in the Parent
domain name field for any resource records created within the
zone.
domain
tree
In DNS, the inverted
hierarchical tree structure that is used to index domain names. Domain
trees are similar in purpose and concept to the directory trees used by
computer filing systems for disk storage.
For example, when
numerous files are stored on disk, directories can be used to organize the
files into logical collections. When a domain tree has one or more
branches, each branch can organize domain names used in the namespace into
logical collections.
In Active Directory, a
hierarchical structure of one or more domains, connected by transitive,
bidirectional trusts, that forms a contiguous namespace. Multiple domain
trees may belong to the same forest.
dots per inch
(DPI)
The standard used to
measure screen and printer resolution, expressed as the number of dots
that a device can display or print per linear inch. The greater the number
of dots per inch, the better the resolution.
double-byte
characters
A set of characters in
which each character is represented by two bytes. Some languages, such as
Japanese, Chinese, and Korean, require double-byte character
sets.
downloadable
fonts
A set of characters
stored on disk and sent (downloaded) to a printer's memory when needed for
printing a document. Downloadable fonts are most commonly used with laser
printers and other page printers, although many dot-matrix printers can
accept some of them. Downloadable fonts are also called soft
fonts.
drag
To move an item on the
screen by selecting the item and then pressing and holding down the mouse
button while moving the mouse. For example, you can move a window to
another location on the screen by dragging its title
bar.
drain
For Network Load
Balancing, a command that disables new traffic handling for the rule whose
port range contains the specified port. All ports specified by the port
rule are affected.
drainstop
For Network Load
Balancing, a command that disables all new traffic handling on the
specified hosts. The hosts then enter draining mode to complete existing
connections.
While draining, hosts
remain in the cluster and stop their cluster operations when there are no
more active connections. To terminate draining mode, explicitly stop
cluster mode with the stop command, or restart new traffic handling
with the start command. To drain connections from a specific port,
use the drain command.
drive
An area of storage that
is formatted with a file system and has a drive letter. The storage can be
a floppy disk, a CD, a hard disk, or another type of disk. You can view
the contents of a drive by clicking its icon in Windows Explorer or My
Computer.
drive
letter
The naming convention for
disk drives on IBM and compatible computers. Drives are named by letter,
beginning with A, followed by a colon.
drop
folder
In the Macintosh
environment, a folder for which you have the Make Changes permission but
not the See Files or See Folders permission. You can copy files into a
drop folder, but you cannot see what files and subfolders the drop folder
contains.
dual boot
A computer configuration
that can start two different operating systems.
duplex
A system capable of
transmitting information in both directions over a communications
channel.
DVD
decoder
A hardware or software
component that allows a digital video disc (DVD) drive to display movies
on your computer screen.
DVD drive
A disk storage device
that uses digital video disc (DVD) technology. A DVD drive reads both
CD-ROM and DVDs; however, you must have a DVD decoder to display DVD
movies on your computer screen.
DWORD
A data type composed of
hexadecimal data with a maximum allotted space of 4
bytes.
dynamic data exchange
(DDE)
A form of interprocess
communication (IPC) implemented in the Microsoft Windows family of
operating systems. Two or more programs that support dynamic data exchange
(DDE) can exchange information and commands.
dynamic
disk
A physical disk that can
be accessed only by Windows 2000 and Windows XP. Dynamic disks
provide features that basic disks do not, such as support for volumes that
span multiple disks. Dynamic disks use a hidden database to track
information about dynamic volumes on the disk and other dynamic disks in
the computer. You convert basic disks to dynamic by using the Disk
Management snap-in or the DiskPart command line utility. When you convert
a basic disk to dynamic, all existing basic volumes become dynamic
volumes.
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.
dynamic
storage
A storage method in
Windows that allows disk and volume management without requiring operating
system restart.
dynamic
update
An updated specification
to the Domain Name System (DNS) standard that permits hosts that store
name information in DNS to dynamically register and update their records
in zones maintained by DNS servers that can accept and process dynamic
update messages.
dynamic
volume
A volume that resides on
a dynamic disk. Windows supports five types of dynamic volumes: simple,
spanned, striped, mirrored, and RAID-5. A dynamic volume is formatted by
using a file system, such as FAT or NTFS, and it has a drive letter
assigned to it.
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.
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