Network Terms "U"

UDF (Uniqueness Database File)

A database containing supplementary information for a Windows 2000 answer file. For example, a UDF may contain the unique IDs, user data, and other information that varies for each installation.

UDP (User Datagram Protocol)

The is a connectionless communications service that does not guarantee delivery of packets. Applications using UDP typically deliver small amounts of data and the application has the responsibility for reliable delivery.

Unattended installation

A method of installing Windows 2000 using an answer file that automates the installation so you do not have to be physically present at the computer during the installation.

UNC (Universal Naming Convention)

A standardized convention used for describing network servers. UNC names start with two backslashes followed by the server computer name, and then the shared folder name. For example, \\server_name\users\%username%

Unicast

Unicast is a transmission method in which packets are sent from a single host to a single host.

Unicode characters

The set of letters, numbers, and symbols that SQL Server recognizes in the nchar, nvarchar, and ntext data types. It includes characters for most languages. Unicode is related to character sets, but is not the same thing, having some 200 times as many possible values and requiring twice the storage space.

Unified Messaging server

The Unified Messaging server automates and integrates voice, e-mail, and fax communications in a single store within the Exchange environment which is accessible through either telephone or the computer. The Unified Messaging server communicates with an IP-based phone system which directs all voicemails to the Unified Messaging server. All voicemails are converted to windows media audio files which are then sent to the user's Mailbox server and stored as attachments in an e-mail. The Unified Messaging server also supports voice-prompt calendar and planning services.

Uniform Resource Locator (URL)

The address of a World Wide Web page, graphic file, or program file on the Internet. Each resource has an exclusive address (URL) that allows your computer to find and display it. The URL includes the code for the transfer protocol, plus the unique name of the Web server containing the page. For example, http://www.universal.com/widgets uses the Hypertext Transfer Protocol (http://) to connect to a specific server (www.universal.com) and display a specific Web page (/widgets).

Uninterruptible Power Supply (UPS)

A power supply that is typically used on file servers to provide battery backup power in case of a power failure. The UPS provides power to a server until an emergency shutdown of the system can occur.

Uniqueness Database File (UDF)

A database containing supplementary information for a Windows 2000 answer file. For example, a UDF may contain the unique IDs, user data, and other information that varies for each installation.

Universal Naming Convention (UNC)

A standardized convention used for describing network servers. UNC names start with two backslashes followed by the server computer name, and then the shared folder name. For example, \\server_name\users\%username%

Universal Serial Bus (USB)

A Universal Serial Bus (USB) is a type of media (cable and connectors) that interface between computer and external devices (hubs, audio players, joysticks, keyboards, telephones, scanners, and printers). A network can be created by linking USB cables between multiple computers.

UNIX

An operating system invented at Bell Labs in 1969. UNIX is a non-proprietary operating system, so there are many independently-produced versions of UNIX, called "flavors."

UNIX LPD print server

A server running the line printer daemon (LPD) service, which allows you to print documents from a remote computer.

Unreachable queue

Unreachable queues hold messages that cannot be routed to their destination due to configuration changes or modified routing paths in Exchange 2007. Each transport server can have only one unreachable queue.

Unshielded Twisted Pair (UTP)

Twisted pair cables support a wide variety of fast, modern network standards. Twisted pair cabling is composed of  two wires that carry the data signals. PVC plastic insulation surrounds each wire. Two wires are twisted to reduce the effects of electromagnetic interference and crosstalk. Because the wires are twisted, EMI should affect both wires equally and can be cancelled out. Multiple wire pairs are bundled together in an outer sheath. Twisted pair cable can be classified according to the makeup of the outer sheath. Unshielded Twisted Pair (UTP) does not have a grounded outer copper shield. UTP cables are easier to work with and are less expensive than shielded cables.

Update messages

Update messages notify all routers in a network of any updates that have been made within the network.

Update Sequence Number (USN)

Servers track directory changes using Update Sequence Numbers (USNs). Each server keeps track of the changes it has already received or made. When a server requests changes from another server, they compare USNs. If the numbers are the same, neither server makes any changes. If one server's number is higher than another, the server with the lower number requests the changes corresponding to the higher numbers.

In Windows 2000, a USN is a server-specific 64-bit counter that increases each time that domain controller's Active Directory database is updated. See also local update sequence number and originating update sequence number.

UPS (Uninterruptible Power Supply)

A power supply that is typically used on file servers to provide battery backup power in case of a power failure. The UPS provides power to a server until an emergency shutdown of the system can occur.

Up-to-date vector

A server's highest originating USN received from a particular originating domain controller. For example, if Server1 has received originating updates from Server6 corresponding to Server6's local USN value 4653, then Server1's up-to-date vector for Server6 is Server6-4653.

URL (Uniform Resource Locator)

The address of a World Wide Web page, graphic file, or program file on the Internet. Each resource has an exclusive address (URL) that allows your computer to find and display it. The URL includes the code for the transfer protocol, plus the unique name of the Web server containing the page. For example, http://www.universal.com/widgets uses the Hypertext Transfer Protocol (http://) to connect to a specific server (www.universal.com) and display a specific Web page (/widgets).

USB (Universal Serial Bus)

A Universal Serial Bus (USB) is a type of media (cable and connectors) that interface between computer and external devices (hubs, audio players, joysticks, keyboards, telephones, scanners, and printers). A network can be created by linking USB cables between multiple computers.

User account

A user name and password that allows a user to log on to a domain or a local computer and gain access to resources.

User Datagram Protocol (UDP)

The is a connectionless communications service that does not guarantee delivery of packets. Applications using UDP typically deliver small amounts of data and the application has the responsibility for reliable delivery.

User Manager for Domains

The Windows NT tool used to manage the security for domains, member servers, and workstations. If the computer is not configured as a domain controller, User Manager is installed. Windows 2000 uses Active Directory Users and Computers instead.

User mode

A mode in which applications run. User mode confines each application to its own address space and does not allow any application to access the computer's hardware directly.

User profile

A file that specifies which Windows 2000 elements are loaded by the system when a user logs on. Included are program items, screen colors, network connections, printer connections, mouse settings, window size, and window position.

When a user logs on for the first time from a Windows-based client, the operating system creates a default profile for that user. A user profile can also be customized to restrict what users see in their interface and have available when they log on.

User rights

The rights that a user has been granted to access files, printers, and applications in a Windows environment.

User rights policy

An account policy in Windows NT that manages the assignment of rights to groups and user accounts.

Username

A the name given to a user's account in a Windows environment. Each user account must have a username and password.

Users

A user in a local group is someone who has been given permission to access a network resource such as access to a folder, file, or printer.

USN (Update Sequence Number)

Servers track directory changes using Update Sequence Numbers (USNs). Each server keeps track of the changes it has already received or made. When a server requests changes from another server, they compare USNs. If the numbers are the same, neither server makes any changes. If one server's number is higher than another, the server with the lower number requests the changes corresponding to the higher numbers.

In Windows 2000, a USN is a server-specific 64-bit counter that increases each time that domain controller's Active Directory database is updated. See also local update sequence number and originating update sequence number.

UTP (Unshielded Twisted Pair)

Twisted pair cables support a wide variety of fast, modern network standards. Twisted pair cabling is composed of  two wires that carry the data signals. PVC plastic insulation surrounds each wire. Two wires are twisted to reduce the effects of electromagnetic interference and crosstalk. Because the wires are twisted, EMI should affect both wires equally and can be cancelled out. Multiple wire pairs are bundled together in an outer sheath. Twisted pair cable can be classified according to the makeup of the outer sheath. Unshielded Twisted Pair (UTP) does not have a grounded outer copper shield. UTP cables are easier to work with and are less expensive than shielded cables.

UUENCODE

UUENCODE was the first widely-used format for binary attachments. It is still an alternative to MIME. It comes in several different flavors, due to different implementations, but it characteristically sends attachments as encoded 7-bit text strings.