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A
A (address) resource
record
A resource record used to map a DNS
domain name to a host IP address on the network.
access control
A security mechanism that determines
which operations a user, group, service, or computer is authorized to
perform on a computer or on a particular object, such as a file, printer,
registry key, or directory service object.
access control entry
(ACE)
An entry in an object's
discretionary access control list (DACL) that grants permissions to a user
or group. An ACE is also an entry in an object's system access control
list (SACL) that specifies the security events to be audited for a user or
group.
account lockout
A Windows security feature that
locks a user account if a number of failed logon attempts occur within a
specified amount of time, based on security policy lockout settings.
Locked accounts cannot log on.
acknowledgment
message
For Message Queuing, a message class
that indicates that a message arrived or was retrieved by the target
application (a positive acknowledgment), or that an error occurred before
the original message could be retrieved (a negative acknowledgment). These
messages are sent to administration queues on the source
computer.
active
Describes the window or icon that
you are currently using or that is currently selected. The operating
system always applies the next keystroke or command you choose to the
active window. Windows or icons on the desktop that are not selected are
inactive.
active content
Dynamic content, such as a stock
ticker, a weather map, or news, that is usually updated from the World
Wide Web or a channel.
Active Directory
The directory service that stores
information about objects on a network and makes this information
available to users and network administrators. Active Directory gives
network users access to permitted resources anywhere on the network using
a single logon process. It provides network administrators with an
intuitive, hierarchical view of the network and a single point of
administration for all network objects.
Active Directory data
model
A model derived from the LDAP data
model. The directory holds objects that represent entities of various
sorts, described by attributes. The objects and classes of objects that
can be stored in the directory are defined in the schema. For each class
of objects, the schema defines the attributes an instance of the class
must have, the additional attributes it can have, and the class that can
be its parent.
Active Directory Users and
Computers
An administrative tool designed to
perform day-to-day Active Directory administration tasks. These tasks
include creating, deleting, modifying, moving, and setting permissions on
objects stored in the directory. These objects include organizational
units, users, contacts, groups, computers, printers, and shared file
objects.
active partition
A partition from which an x86-based
computer starts up. The active partition must be a primary partition on a
basic disk. If you use Windows exclusively, the active partition can be
the same as the system volume.
active volume
The volume from which the computer
starts up. The active volume must be a simple volume on a dynamic disk.
You cannot mark an existing dynamic volume as the active volume, but you
can upgrade a basic disk containing the active partition to a dynamic
disk. Once the disk is upgraded to dynamic, the partition becomes a simple
volume that is active.
ActiveX
A set of technologies that allows
software components to interact with one another in a networked
environment, regardless of the language in which the components were
created.
address (A) resource
record
A resource record used to map a DNS
domain name to a host IP address on the network.
address classes
Predefined groupings of Internet
addresses with each class defining networks of a certain size. The range
of numbers that can be assigned for the first octet in the IP address is
based on the address class. Class A networks (values 1 to 126) are the
largest, with more than 16 million hosts per network. Class B networks
(128 to 191) have up to 65,534 hosts per network, and Class C networks
(192 to 223) can have up to 254 hosts per network.
Address Resolution Protocol
(ARP)
In TCP/IP, a protocol that uses
broadcast traffic on the local network to resolve a logically assigned IP
address to its physical hardware or media access control layer address.
In ATM, ARP is used two different
ways. For classical IP over ATM, ARP is used to resolve addresses to ATM
hardware addresses. For ATM LAN emulation, ARP is used to resolve
Ethernet/802.3 or Token Ring addresses to ATM hardware
addresses.
administration queue
For Message Queuing, a queue that
stores acknowledgment messages.
administrative alerts
Alerts that relate to server and
resource use. They notify users about problems in areas such as security
and access, user sessions, server shutdown due to power loss (when an
uninterruptible power supply is available), directory replication, and
printing. When a computer generates an administrative alert, a message is
sent to a predefined list of users and computers.
administrator
For Windows XP Professional, a
person responsible for setting up and managing domain controllers or local
computers and their user and group accounts, assigning passwords and
permissions, and helping users with networking problems. Administrators
are members of the Administrators group and have full control over the
domain or computer.
For Windows XP Home Edition, a
person who can make system-wide changes to the computer, install software,
and who has access to all files on the computer. A person with a computer
administrator account has full access to other user accounts on the
computer.
Advanced Configuration and Power
Interface (ACPI)
An open industry specification that
defines power management on a wide range of mobile, desktop, and server
computers and peripherals. ACPI is the foundation for the OnNow industry
initiative that allows system manufacturers to deliver computers that will
start at the touch of a keyboard. ACPI design is essential to take full
advantage of power management and Plug and Play.
affinity
For Network Load Balancing, the
method used to associate client requests to cluster hosts. When no
affinity is specified, all network requests are load balanced across the
cluster without respect to their source. Affinity is implemented by
directing all client requests from the same IP address to the same cluster
host.
agent
An application that runs on a Simple
Network Management Protocol (SNMP) managed device. The agent application
is the object of management activities. A computer running SNMP agent
software is also sometimes referred to as an agent.
Alerter service
A service used by the server and
other services to notify selected users and computers of administrative
alerts that occur on a computer. The Alerter service requires the
Messenger service.
allocation unit
The smallest amount of disk space
that can be allocated to hold a file. All file systems used by Windows
organize hard disks based on allocation units. The smaller the allocation
unit size, the more efficiently a disk stores information. If you do not
specify an allocation unit size when formatting the disk, Windows picks
default sizes based on the size of the volume. These default sizes are
selected to reduce the amount of space that is lost and the amount of
fragmentation on the volume. An allocation unit is also called a
cluster.
American Standard Code for
Information Interchange (ASCII)
A standard single-byte character
encoding scheme used for text-based data. ASCII uses designated 7-bit or
8-bit number combinations to represent either 128 or 256 possible
characters. Standard ASCII uses 7 bits to represent all uppercase and
lowercase letters, the numbers 0 through 9, punctuation marks, and special
control characters used in U.S. English. Most current x86-based systems
support the use of extended (or "high") ASCII. Extended ASCII allows the
eighth bit of each character to identify an additional 128 special symbol
characters, foreign-language letters, and graphic symbols.
AppleTalk
The Apple Computer network
architecture and network protocols. A network that has Macintosh clients
and a computer running Windows 2000 Server or Windows NT Server with
Services for Macintosh functions as an AppleTalk network.
AppleTalk Phase 2
The extended AppleTalk Internet
model designed by Apple Computer that supports multiple zones within a
network and extended addressing capacity.
application programming interface
(API)
A set of routines that an
application uses to request and carry out lower-level services performed
by a computer's operating system. These routines usually carry out
maintenance tasks such as managing files and displaying
information.
ASCII (American Standard Code for
Information Interchange)
Assistive Technology
Program
A service that provides
recommendations for technology that can help people with
disabilities.
Asymmetric Digital Subscriber Line
(ADSL)
A high-bandwidth digital
transmission technology that uses existing phone lines and also allows
voice transmissions over the same lines. Most of the traffic is
transmitted downstream to the user, generally at rates of 512 Kbps to
about 6 Mbps.
asynchronous
communication
A form of data transmission in which
information is sent and received at irregular intervals, one character at
a time. Because data is received at irregular intervals, the receiving
modem must be signaled to let it know when the data bits of a character
begin and end. This is done by means of start and stop bits.
Asynchronous Transfer Mode
(ATM)
A high-speed connection-oriented
protocol used to transport many different types of network traffic. ATM
packages data in a 53-byte, fixed-length cell that can be switched quickly
between logical connections on a network.
ATM adaptation layer
(AAL)
The layer of the ATM protocol stack
that parses data into the payload portion of the ATM cell for transport
across an ATM network.
attribute
For files, information that
indicates whether a file is read-only, hidden, ready for archiving
(backing up), compressed, or encrypted, and whether the file contents
should be indexed for fast file searching.
In Active Directory, characteristics
of an object and the type of information an object can hold. For each
object class, the schema defines what attributes an instance of the class
must have and what additional attributes it might have.
audio input device
An audio input device records music
and voice input into your computer. Examples of audio input devices are
CD-ROM players and microphones.
audit policy
A policy that determines the
security events to be reported to the network administrator.
auditing
The process that tracks the
activities of users by recording selected types of events in the security
log of a server or a workstation.
authentication
The process for verifying that an
entity or object is who or what it claims to be. Examples include
confirming the source and integrity of information, such as verifying a
digital signature or verifying the identity of a user or
computer.
authoritative
For DNS, describes a DNS server
hosting a zone, or a zone containing a name or record. When a DNS server
is configured to host a zone, it is said to be authoritative for names
that do exist or could exist within that zone. A DNS server is allowed to
respond authoritatively to queries for domain names for which it is
authoritative. A zone is said to be authoritative for a name if the name
exists or could exist within a zone, and it is said to be authoritiative
for a record if the owner name of the record exists or could exist within
a zone.
authoritative restore
In Backup, a type of restore
operation performed on an Active Directory domain controller in which the
objects in the restored directory are treated as authoritative, replacing
(through replication) all existing copies of those objects. Authoritative
restore is applicable only to replicated system state data such as Active
Directory data and File Replication service data. Use the Ntdsutil.exe
utility to perform an authoritative restore.
authorization
The process that determines what a
user is permitted to do on a computer system or network.
Automatic Private IP Addressing
(APIPA)
A feature of Windows XP TCP/IP
that automatically configures a unique IP address from the range
169.254.0.1 through 169.254.255.254 and a subnet mask of 255.255.0.0 when
the TCP/IP protocol is configured for dynamic addressing and a Dynamic
Host Configuration Protocol (DHCP) is not available.
availability
A measure of the fault tolerance of
a computer and its programs. A highly available computer runs 24 hours a
day, 7 days a week. |
