Windows Glossary “Windows Dictionary” (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.

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.