T

T1

A wide-area carrier that transmits data at 1.544 Mbps. A T1 line is also known as DS-1 line.

T3

A wide-area carrier that transmits data at 44.736 Mbps. A T3 line is also known as a DS-3 line.

Task Offload

A process that allows tasks normally performed by the transport layer to be processed by the network adapter. This reduces the overhead required of the system CPU for these tasks, thus increasing the throughput.

taskbar

The bar that contains the Start button and appears by default at the bottom of the desktop. You can use the taskbar buttons to switch between the programs you are running. The taskbar can be hidden, moved to the sides or top of the desktop, or customized in other ways. See also desktop; taskbar button; status area.

taskbar button

A button that appears on the taskbar when an application is running. See also taskbar.

TCP

Transmission Control Protocol.

TCP connection

The logical connection that exists between two processes that are using TCP to exchange data.

TCP segment

The quantity consisting of the TCP header and its associated data. TCP segments are exchanged using a TCP connection.

TCP timestamps

The TCP option used to record the time a TCP segment was sent and a time the segment was acknowledged by the receiver.

TCP Window Scaling

The use of TCP options to create a TCP receive window size greater than 65,535 bytes. The use of TCP window scaling can improve TCP throughput in large bandwidth, high-delay environments.

TCP/IP

See Transmission Control Protocol/Internet Protocol.

TCP/IP filtering

A feature of Windows 2000 TCP/IP that allows you to specify exactly which types of incoming non-transit IP traffic are processed for each IP interface.

Telephony API (TAPI)

An application programming interface (API) used by communications programs to communicate with telephony and network services. See also Internet Protocol.

Telnet

A terminal-emulation protocol that is widely used on the Internet to log on to network computers. Telnet also refers to the application that uses the Telnet protocol for users who log on from remote locations.

Telnet 3270 (TN3270)

Terminal emulation software, similar to Telnet, that allows a personal computer to log on to an IBM mainframe over a TCP/IP network.

Telnet 5250 (TN5250)

Terminal emulation software, similar to Telnet, that allows a personal computer to log on to an IBM AS/400 host system over a TCP/IP network.

terminal

A device consisting of a display screen and a keyboard that is used to communicate with a computer.

text mode

The portion of Setup that uses a text-based interface.

thin client

A network computer that does not have a hard disk.

thread

A type of object within a process that runs program instructions. Using multiple threads allows concurrent operations within a process and enables one process to run different parts of its program on different processors simultaneously. A thread has its own set of registers, its own kernel stack, a thread environment block, and a user stack in the address space of its process.

thread state

A numeric value indicating the execution state of the thread. Numbered 0 through 5, the states seen most often are 1 for ready, 2 for running, and 5 for waiting.

three-way handshake

The series of three TCP segments that are exchanged when a TCP connection is established.

throughput

For disks, the transfer capacity of the disk system.

Tick Count

An estimate of the amount of time it takes an IPX packet to reach the destination network.

ticket-granting ticket

A credential issued to a user by the Key Distribution Center (KDC) when the user logs on. The user must present the TGT to the KDC when requesting session tickets for services. Because a TGT is normally valid for the life of the user's logon session, it is sometimes called a user ticket. See also Kerberos authentication protocol; Key Distribution Center; session ticket.

Time Service

A server cluster resource that maintains consistent time across all nodes.

Time To Live (TTL)

A timer value included in packets sent over TCP/IP-based networks that tells the recipients how long to hold or use the packet or any of its included data before expiring and discarding the packet or data. For DNS, TTL values are used in resource records within a zone to determine how long requesting clients should cache and use this information when it appears in a query response answered by a DNS server for the zone.

ToggleKeys

A Windows feature that beeps when one of the locking keys (CAPS LOCK, NUM LOCK, or SCROLL LOCK) is turned on or off.

Token Ring

A type of network media that connects clients in a closed ring and uses token passing to allow clients to use the network. See also Fiber Distributed Data Interface (FDDI).

tombstone

In Active Directory, an object that is removed from the directory but not yet deleted.

tombstone lifetime

The length of time that an object lives as a tombstone in the directory before being collected as garbage.

top-level domains

Domain names that are rooted hierarchically at the first tier of the domain namespace, directly beneath the root (.) of the DNS namespace. On the Internet, top-level domain names such as ".com" and ".org" are used to classify and assign second-level domain names (such as "microsoft.com") to individual organizations and businesses according to their organizational purpose. See also second-level domains.

topology

In Windows operating systems, the relationships among a set of network components. In the context of Active Directory replication, topology refers to the set of connections that domain controllers use to replicate information among themselves. See also domain controller; replication.

total instance

A unique instance that contains the performance counters that represent the sum of all active instances of an object.

totally stubby area

An OSPF area that does not advertise individual external networks or OSPF inter-area routes. A router's routing table within a totally stubby area contains intra-area routes and a default route (destination 0.0.0.0 with the network mask of 0.0.0.0). The default route summarizes all inter-area routes and all external routes.

tracing

A capability of components of the Windows 2000 Routing and Remote Access service that records internal component variables, function calls, and interactions. You can use tracing to troubleshoot complex network problems.

Traffic Control

A Windows 2000 mechanism that creates and regulates data flows with defined QoS parameters. The Traffic Control API (TC API) creates filters to direct selected packets through this flow. Traffic control is invoked by the QoS API and subsequently serviced by the RSVP SP.

Transaction Program Monitor

A monitor that manages the operating environment of the online transaction processing (OLTP) application by optimizing the use of operating system resources and the network. The TP Monitor provides a management platform for the system administrator that supports: load balancing, fault tolerance, performance monitoring, and security.

transform

A custom script created to customize the behavior of an installation by directly modifying the setup script and without repacking the application.

transit internetwork

The shared or public internetwork crossed by the encapsulated data.

transitive trust relationship

The trust relationship that inherently exists between Windows 2000 domains in a domain tree or forest, or between trees in a forest, or between forests. When a domain joins an existing forest or domain tree, a transitive trust is automatically established. In Windows 2000 transitive trusts are always two-way relationships. See also domain tree; forest; nontransitive trust relationship.

Transmission Control Protocol/Internet Protocol (TCP/IP)

A set of software networking protocols widely used on the Internet that provide communications across interconnected networks of computers with diverse hardware architectures and operating systems. TCP/IP includes standards for how computers communicate and conventions for connecting networks and routing traffic.

Transport Driver Interface (TDI)

In the Windows NT and Windows 2000 networking model, a common interface for network layer components. The TDI is not a single program, but a protocol specification to which the upper bounds of transport protocol device drivers are written. It allows software components above and below the transport layer to be mixed and matched without reprogramming.

transport layer

The network layer that handles error recognition and recovery. When necessary, it repackages long messages into small packets for transmission and, at the receiving end, rebuilds packets into the original message. The receiving transport layer also sends receipt acknowledgments.

Transport Layer Security (TLS)

A standard protocol that is used to provide secure Web communications on the Internet or intranets. It enables clients to authenticate servers or, optionally, servers to authenticate clients. It also provides a secure channel by encrypting communications for confidentiality.

transport protocol

A protocol that defines how data should be presented to the next receiving layer in the Windows NT and Windows 2000 networking model and packages the data accordingly. The transport protocol passes data to the network adapter driver through the network driver interface specification (NDIS) interface and to the redirector through the Transport Driver Interface (TDI).

trap

In Simple Network Management Protocol (SNMP), a message sent by an agent to a management system indicating that an event has occurred on the host running the agent. See also agent; authentication; Internet Protocol; Simple Network Management Protocol (SNMP).

trap destination

The management system that receives an SNMP trap message.

Trap message

An SNMP alarm message.

tree-root trust relationship

The trust relationship that is established when you add a new tree to an Active Directory forest. Active Directory installation process automatically creates a transitive trust relationship between the domain you are creating (the new tree root) and the forest root.

trigger

For Network Monitor data captures, a set of conditions defined by a user that, when met, initiate an action such as stopping a capture or executing a program or command file.

triggered update

A route advertising algorithm that advertises changes in the network topology as they occur, rather than waiting for the next scheduled periodic advertisement.

Trivial File Transfer Protocol (TFTP)

A protocol that is used by an IntelliMirror server to download the initial files needed to begin the boot or installation process.

TrueType fonts

Fonts that are scalable and sometimes generated as bitmaps or soft fonts, depending on the capabilities of your printer. TrueType fonts are device-independent fonts that are stored as outlines. They can be sized to any height, and they can be printed exactly as they appear on the screen. See also font.

truncate

To remove files that are in remote storage from local storage, reclaiming space in local storage. When a premigrated file is truncated it is converted to a remote storage identifier or placeholder.

trust path

A series of trust links from one domain to another domain for passing authentication requests.

trust relationship

A logical relationship established between domains that allows pass-through authentication in which a trusting domain honors the logon authentications of a trusted domain. User accounts and global groups defined in a trusted domain can be granted rights and permissions in a trusting domain, even though the user accounts or groups do not exist in the trusting domain's directory. See also authentication; domain; two-way trust relationship.

trusted forest

A forest that is connected to another forest by explicit or transitive trust. See also explicit trust relationship; forest; transitive trust relationship.

TTL

See Time To Live.

tunnel

The logical path by which the encapsulated packets travel through the transit internetwork.

tunneled data

Data that is sent through the tunneled, or encapsulated, portion of the connection.

tunneling

A method of using an internetwork infrastructure of one protocol to transfer a payload (the frames or packets) of another protocol.

tunneling protocol

A communication standard used to manage tunnels and encapsulate private data. Data that is tunneled must also be encrypted to be a VPN connection. Windows 2000 includes the Point-to-Point Tunneling Protocol (PPTP) and Layer 2 Tunneling Protocol (L2TP).

two-way initiated connection

A demand-dial connection where either router can be the answering router or the calling router depending on who is initiating the connection. Both routers must be configured to initiate and accept a demand-dial connection. You use two-way initiated connections when traffic from either router can create the demand-dial connection.

two-way trust relationship

A link between domains in which each domain trusts user accounts in the other domain to use its resources. Users can log on from computers in either domain to the domain that contains their account. See also trust relationship.

U

UDP

See User Datagram Protocol.

unallocated space

Available disk space that is not allocated to any partition, logical drive, or volume. The type of object created on unallocated space depends on the disk type (basic or dynamic). For basic disks, unallocated space outside partitions can be used to create primary or extended partitions. Free space inside an extended partition can be used to create a logical drive. For dynamic disks, unallocated space can be used to create dynamic volumes. Unlike basic disks, the exact disk region used is not selected to create the volume. See also basic disk; dynamic disk; extended partition; logical drive; partition; primary partition; volume.

Unattended Setup

An automated, hands-free method of installing Windows 2000. During installation, Unattended Setup uses an answer file to supply data to Setup instead of requiring that an administrator interactively provide the answers.

UNC

See Universal Naming Convention.

UNC name

A full Windows 2000 name of a resource on a network. It conforms to the \\servername\sharename syntax, where servername is the server's name and sharename is the name of the shared resource. UNC names of directories or files can also include the directory path under the share name, with the following syntax: \\servername\sharename\directory\filename. UNC is also called Universal Naming Convention.

unicast

An address that identifies a specific, globally unique host.

unicast listening mode

A listening mode where the only frames that are considered for further processing are in a table of interesting destination media access control addresses on the network adapter. Typically, the only interesting addresses are the broadcast address (0xFF-FF-FF-FF-FF-FF) and the unicast address, (also known as the media access control address), of the adapter.

Unicode

A fixed-width, 16-bit character-encoding standard capable of representing the letters and characters of the majority of the world's languages. Unicode was developed by a consortium of U.S. computer companies.

Uniform Resource Locator (URL)

An address that uniquely identifies a location on the Internet. A URL for a World Wide Web site is preceded with http://, as in the fictitious URL http://www.example.microsoft.com/. A URL can contain more detail, such as the name of a page of hypertext, usually identified by the file name extension .html or .htm. See also HTML; HTTP; IP address.

uninterruptible power supply (UPS)

A device connected between a computer and a power source to ensure that electrical flow is not interrupted. UPS devices use batteries to keep the computer running for a period of time after a power failure. UPS devices usually provide protection against power surges and brownouts as well.

universal group

A Windows 2000 group only available in native mode that is valid anywhere in the forest. A universal group appears in the Global Catalog but contains primarily global groups from domains in the forest. This is the simplest form of group and can contain other universal groups, global groups, and users from anywhere in the forest. See also domain local group; forest; Global Catalog.

Universal Naming Convention (UNC)

A convention for naming files and other resources beginning with two backslashes (\), indicating that the resource exists on a network computer. UNC names conform to the \\SERVERNAME\SHARENAME syntax, where SERVERNAME is the server's name and SHARENAME is the name of the shared resource. The UNC name of a directory or file can also include the directory path after the share name, with the following syntax: \\SERVERNAME\SHARENAME\DIRECTORY\FILENAME.

Universal Serial Bus (USB)

A serial bus with a bandwidth of 1.5 megabits per second (Mbps) for connecting peripherals to a microcomputer. USB can connect up to 127 peripherals, such as external CD-ROM drives, printers, modems, mice, and keyboards, to the system through a single, general-purpose port. This is accomplished by daisy chaining peripherals together. USB supports hot plugging and multiple data streams.

UNIX

A powerful, multiuser, multitasking operating system initially developed at AT&T Bell Laboratories in 1969 for use on minicomputers. UNIX is considered more portable-that is, less computer-specific-than other operating systems because it is written in C language. Newer versions of UNIX have been developed at the University of California at Berkeley and by AT&T.

unnamed data attribute

The default data stream of an NTFS file, sometimes referred to as $DATA.

unprepared state

A state that indicates a side of a medium that is not claimed or used by any application, but which does not have a free label on it. Applications cannot allocate unprepared media. This is a temporary state.

unrecognized media pool

A repository of blank media and media that are not recognized by Removable Storage.

unrecognized state

A state that indicates that the label types and label IDs of a medium are not recognized by Removable Storage.

up-to-dateness vector

In Active Directory replication, a value that the source domain controller uses to reduce the set of objects and attributes that it sends to the destination domain controller. The up-to-dateness vector is provided to the source domain controller by the destination domain controller and indicates the highest update sequence number (USN) of originating write that has been received for the relevant directory partition from the source domain controller.

update sequence number (USN)

In Active Directory replication, a 64-bit counter that is maintained by each Active Directory domain controller. At the start of each update transaction (originating or replicated) on a domain controller, the domain controller increments its current USN and associates this new value with the update request.

user account

A record that consists of all the information that defines a user to Windows 2000. This includes the user name and password required for the user to log on, the groups in which the user account has membership, and the rights and permissions the user has for using the computer and network and accessing their resources. For Windows 2000 Professional and member servers, user accounts are managed by using Local Users and Groups. For Windows 2000 Server domain controllers, user accounts are managed by using Microsoft Active Directory Users and Computers. See also domain controller; group; user name.

user account objects

Objects used to identify a specific user account in Windows NT Server 4.0 or Windows 2000 Server.

User Datagram Protocol (UDP)

A TCP/IP component that offers a connectionless datagram service that guarantees neither delivery nor correct sequencing of delivered packets.

user mode

The processing mode in which applications run.

user name

A unique name identifying a user account to Windows 2000. An account's user name must be unique among the other group names and user names within its own domain or workgroup.

user network interface (UNI)

The interface between ATM users or end stations and an ATM switch or network. The UNI interface is defined in the ATM Forum UNI documents.

user password

The password stored in each user's account. Each user generally has a unique user password and must type that password when logging on or accessing a server.

user profile

A file which contains configuration information for a specific user, such as desktop settings, persistent network connections, and application settings. Each user's preferences are saved to a user profile that Windows NT and Windows 2000 use to configure the desktop each time a user logs on.

user rights

Tasks a user is permitted to perform on a computer system or domain. There are two types of user rights: privileges and logon rights. An example of a privilege is the right to shut down the system. An example of a logon right is the right to log on to a computer locally (at the keyboard). Both types are assigned by administrators to individual users or groups as part of the security settings for the computer. See also permission; privilege.

user ticket

See ticket-granting ticket.

users

A special group that contains all users who have user permissions on the server. When a Macintosh user assigns permissions to everyone, those permissions are given to the groups' users and guests. See also everyone category; guest.

Utility Manager

A function of Windows 2000 that allows administrators to review the status of applications and tools and to customize features and add tools more easily.

V

value bar

The area of the System Monitor graph or histogram display that shows last, average, minimum and maximum statistics for the selected counter.

variable bit rate (VBR)

An ATM service type that guarantees service based on average and peak traffic rates. VBR is used for traffic that requires little or no cell loss. It transmits data in spurts, or bursts, rather than in a continuous stream.

variable length subnet masks (VLSM)

Subnet masks used to produce subnets of an IP network ID of different sizes.

variable length subnetting

The practice of subdividing the address space of an IP network ID into subnets of different sizes.

version ID

A counter used to determine which WINS database entries must be updated during replication. See also replication.

virtual channel identifier (VCI)

A section of the ATM cell header that contains the virtual channel address over which the cell is to be routed.

Virtual Circuit (VC)

A point-to-point connection for the transmission of data. This allows greater control of call attributes, such as bandwidth, latency, delay variation, and sequencing.

virtual link

A logical link between a backbone area border router and an area border router that is not connected to the backbone.

virtual memory

The space on the hard disk that Windows 2000 uses as memory. Because of virtual memory, the amount of memory taken from the perspective of a process can be much greater than the actual physical memory in the computer. The operating system does this in a way that is transparent to the application, by paging data that does not fit in physical memory to and from the disk at any given instant.

virtual network

A logical network that exists inside Novell NetWare and NetWare-compatible servers and routers but is not associated with a physical adapter. The virtual network appears to a user as a separate network. On a computer running Windows 2000 Server, programs advertise their location on a virtual network, not a physical network. The internal network number identifies a virtual network inside a computer. See also internal network number; external network number.

virtual path identifier (VPI)

A section of the ATM cell header that contains the virtual path address over which the cell is to be routed.

virtual private network (VPN)

The extension of a private network that encompasses links across shared or public networks, such as the Internet.

virtual private network connection

A link in which private data is encapsulated and encrypted.

virtual private networking

The act of configuring and creating a virtual private network.

virtual server

In a server cluster, a set of resources, including a Network Name resource and an IP address resource, that is contained by a resource group. To clients, a virtual server presents the appearance of a system that is running Windows NT Server or Windows 2000 Server.

voice input utility

A type of speech recognition program that allows users with disabilities to control the computer with their voice instead of a mouse or keyboard.

volume

A portion of a physical disk that functions as though it were a physically separate disk. In My Computer and Windows Explorer, volumes appear as local disks, such as drive C or drive D.

volume decommission

A process that occurs when a managed volume is no longer accessible. The data in remote storage is no longer associated with a placeholder or a premigrated file. This space is available for space reclamation.

volume mount points

New system objects in the version of NTFS included with Windows 2000 that represent storage volumes in a persistent, robust manner. Volume mount points allow the operating system to graft the root of a volume onto a directory.

volume set

A combination of partitions on a physical disk that appears as one logical drive. See also fault tolerance; stripe set.

VPN

See virtual private network.

VPN client

A computer that initiates a VPN connection to a VPN server. A VPN client can be an individual computer that obtains a remote access VPN connection or a router that obtains a router-to-router VPN connection.

VPN connection

The portion of the connection in which your data is encrypted.

VPN server

A computer that accepts VPN connections from VPN clients. A VPN server can provide a remote access VPN connection or a router-to-router VPN connection.

W

Wake-On-LAN

A feature that controls shut down and wake-up based on network events such as lack of network activity or disconnection.

WAN

See wide area network.

Web farm

A Network Load Balancing cluster of IIS servers that support client Web site requests.

Web server

A server that provides the ability to develop COM-based applications and to create large sites for the Internet and corporate intranets.

Well-Known Ports

Ports in the range from 0 - 1023.

wide area network (WAN)

A communications network connecting geographically separated computers, printers, and other devices. A WAN allows any connected device to interact with any other on the network. See also local area network (LAN).

wildcard

In DNS, a character that can be substituted for another character during a query.

Windows 2000 MultiLanguage Version

A version of Windows 2000 that extends the native language support in Windows 2000 by allowing user interface languages to be changed on a per user basis. This version also minimizes the number of language versions you need to deploy across the network.

Windows 2000 Redirector

A software component that intercepts network requests and redirects them to network servers, workstations, printers and directory shares.

Windows 2000 Setup

The program that installs Windows 2000. Also known as Setup, Winnt32.exe, and Winnt.exe.

Windows Driver Model (WDM)

A specification for I/O device drivers that supports both Windows 2000 and Windows 98. WDM is based on a class/miniport driver architecture that is modular and extensible. WDM easier for hardware vendors to support hardware devices.

Windows Installer (.msi files)

An operating system service that allows the operating system to manage the installation process. Windows Installer technologies are divided into two parts that work in combination: a client-side installer service (MSIEXEC.EXE) and a package file (.msi file). Windows Installer uses the information contained within a package file to install the application.

Windows Internet Name Service (WINS)

A software service that dynamically maps IP addresses to computer names (NetBIOS names). This allows users to access resources by name instead of requiring them to use IP addresses that are difficult to recognize and remember. WINS servers support clients running Windows NT 4.0 and earlier versions of Windows operating systems. See also Domain Name System (DNS).

Windows Management Instrumentation

Microsoft technology used to extend the Desktop Management Task Force (DMTF) Web-Based Enterprise Management (WBEM) initiative by representing physical and logical objects that exist in Windows management environments in a consistent and unified manner. WMI is designed to simplify the development of well-integrated management applications, allowing vendors to provide highly efficient, scalable management solutions for enterprise environments.

Windows NT 4.0-compatible Locator

See domain controller locator.

Windows Sockets (Winsock)

An industry-standard application programming interface (API) used on the Microsoft Windows operating system that provides a two-way, reliable, sequenced, and unduplicated flow of data.

Windows-based terminal

A terminal that uses a Windows operating system.

WinInstall LE

A repackaging tool that comes with Windows 2000 Server.

WINS

See Windows Internet Name Service.

WINS database

The database used to register and resolve computer names to IP addresses on Windows-based networks. The contents of this database are replicated at regular intervals throughout the network. See also push partner, pull partner, replication.

WINS lookup

A process by which a DNS server queries WINS to resolve names it does not find in its authoritative zones.

WINS proxy

A computer that listens to name query broadcasts and responds for those names not on the local subnet. The proxy communicates with a WINS server to resolve names and then caches them for a specific time period. See also Windows Internet Name Service (WINS).

WINS referral zone

A zone that refers DNS queries to WINS.

wire protocol

A protocol that defines the formats of client and server messages and interactions with various application programming interfaces (APIs), which provide programmatic access to these protocols.

working set

For a process, the amount of physical memory assigned to a process by the operating system.

Workstation service

The system service that provides network connections and communications.

X

X.509 version 3 certificate

Version 3 of the ITU-T recommendation X.509 for syntax and format. This is the standard certificate format used by Windows 2000 certificate-based processes. An X.509 certificate includes the public key and information about the person or entity to whom the certificate is issued, information about the certificate, plus optional information about the certification authority (CA) issuing the certificate. See also certificate; public key.

Y

Z

ZAP (.zap) file

Zero Administration Windows application package file. A text file (similar to an .ini file) that describes how to install an application (which command line to use); the properties of the application (name, version, and language); and what entry points the application should automatically install (for file name extension, CLSID, and ProgID). A .zap file is generally stored in the same location on the network as the setup program it references.

zone

In a DNS database, a zone is a contiguous portion of the DNS tree that is administered as a single separate entity by a DNS server. The zone contains resource records for all the names within the zone. In the Macintosh environment, a logical grouping that simplifies browsing the network for resources, such as servers and printers. It is similar to a domain in Windows 2000 Server networking. See also domain; Domain Name System (DNS); DNS server.

zone file

A text file on a DNS name server containing resource records for a zone. See also zone.

zone list

In the Macintosh environment, a list that includes all of the zones associated with a particular network. Not to be confused with Windows 2000 DNS zones. See also zone.

zone transfer

The process by which DNS servers interact to maintain and synchronize authoritative name data. When a DNS server is configured as a secondary server for a zone, it periodically queries the master DNS server configured as its source for the zone. If the version of the zone kept by the master is different than the version on the secondary server, the secondary server will pull zone data from its master DNS server to update zone data. See also full zone transfer (AXFR); incremental zone transfer (IXFR); secondary server; zone.