Windows Server 2003 Glossary - H

Article
10/08/2009

Applies To: Windows Server 2000, Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

For more Windows Server terms, see the Windows Server 2008 Glossary.

Glossary - H

# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

H.323

The International Telecommunication Union - Telecommunication (ITU-T) standard for packet-based multimedia communications.

See also: International Telecommunication Union - Telecommunication [Standardization Sector] (ITU-T) packet

half-duplex

A system capable of transmitting information in only one direction at a time over a communications channel.

handle

In the user interface, an interface added to an object that facilitates moving, sizing, reshaping, or other functions pertaining to an object. In programming, a pointer to a pointer, that is, a token that lets a program access an identified resource.

handle count

In Task Manager, the number of object handles in a process`s object table.

handshaking

A series of signals acknowledging that communication can take place between computers or other devices. A hardware handshake is an exchange of signals over specific wires (other than the data wires), in which each device indicates its readiness to send or receive data. A software handshake consists of signals transmitted over the same wires used to transfer data, as in modem-to-modem communications over telephone lines.

See also: device modem (modulator/demodulator)

Hardware Compatibility List (HCL)

A hardware list that Microsoft compiled for specific products, including Windows 2000 and earlier versions of Windows. The list for a specific product, such as Windows 2000, includes the hardware devices and computer systems that are compatible with that version of the product. For products in the Windows Server 2003 family, you can find the equivalent information on the Windows Catalog Web site.

hardware compression

A feature available on some tape devices that automatically compresses the data that is being stored on the device. This is usually an option that is turned on or off in a backup program.

hardware configuration

Resource settings that have been allocated for a specific device. Each device on your computer has a hardware configuration, which can consist of interrupt request (IRQ) lines, direct memory access (DMA), an input/output (I/O) port, or memory address settings.

See also: device direct memory access (DMA) input/output (I/O) port interrupt request (IRQ) lines memory address

hardware decoder

A type of digital video disc (DVD) decoder that allows a DVD drive to display movies on your computer screen. A hardware decoder uses both software and hardware to display movies.

See also: DVD decoder DVD drive software decoder

hardware profile

Data that describes the configuration and characteristics of specific computer equipment. This information can be used to configure computers for using peripheral devices.

hardware type

A classification for similar devices. For example, Imaging Device is a hardware type for digital cameras and scanners.

hash

A fixed-size result that is obtained by applying a one-way mathematical function (sometimes called a hash algorithm) to an arbitrary amount of data. If there is a change in the input data, the hash changes. The hash can be used in many operations, including authentication and digital signing. Also called a message digest.

hash algorithm

An algorithm that produces a hash value of some piece of data, such as a message or session key. With a good hash algorithm, changes in the input data can change every bit in the resulting hash value; for this reason, hashes are useful in detecting any modification in a data object, such as a message. Furthermore, a good hash algorithm makes it computationally infeasible to construct two independent inputs that have the same hash. Typical hash algorithms include MD2, MD4, MD5, and SHA-1. Also called a hash function.

See also: Hash-based Message Authentication Mode (HMAC) MD2 MD4 MD5 message digest Secure Hash Algorithm (SHA-1)

Hash-based Message Authentication Mode (HMAC)

A mechanism for message authentication using cryptographic hash functions. HMAC can be used with any iterative cryptographic hash function (for example, MD5 and SHA-1) in combination with a secret shared key. The cryptographic strength of HMAC depends on the properties of the underlying hash function.

See also: hash algorithm MD5 Secure Hash Algorithm (SHA-1)

HCL

See other term: Hardware Compatibility List (HCL)

header error control (HEC)

The fifth byte in the asynchronous transfer mode (ATM) cell header used to detect and correct errors in the ATM header.

See also: asynchronous transfer mode (ATM)

headless server

See other term: remotely administered server

heartbeat

A signal emitted at regular intervals by software to indicate that it is still running.

See also: Network Load Balancing Network Load Balancing cluster server cluster

HEC

See other term: header error control (HEC)

heterogeneous environment

An internetwork with servers and workstations running different operating systems, such as Microsoft Windows, Apple Macintosh, or Novell NetWare, using a mix of different transport protocols.

hexadecimal

A base-16 number system represented by the digits 0 through 9 and the uppercase or lowercase letters A (equivalent to decimal 10) through F (equivalent to decimal 15).

high availability

For server clusters, the restarting of a failed application or the dispersion of the work to remaining computers when a computer or application in the server cluster fails.

histogram

A chart consisting of horizontal or vertical bars, the widths or heights of which represent the values of certain data.

hive

A file in which the system stores a portion of the registry (named for their resemblance to the cellular structure of a beehive). A hive is backed by a single file and a .log file, which are in either the %SYSTEMROOT%\System32\Config folder or the %SYSTEMROOT%\Profiles\%USERNAME% folder. By default, most hive files (Default, SAM, Security, and System) are stored in the %SYSTEMROOT%\System32\Config folder. The %SYSTEMROOT%\Profiles folder contains the user profile for each user of the computer. Because a hive is a file, it can be moved from one system to another. However, you must use the Registry Editor, Regedit.exe, to edit the file.

HMAC

See other term: Hash-based Message Authentication Mode (HMAC)

home folder

A folder (usually on a file server) that administrators can assign to individual users or groups. Administrators use home folders to consolidate user files onto specific file servers for easy backup. Home folders are used by some programs as the default folder for the Open and Save As dialog boxes. Sometimes referred to as home directories.

hop count

The value in the Transport Control field that indicates the number of Internetwork Packet Exchange (IPX) routers that have processed the IPX packet.

See also: Internetwork Packet Exchange (IPX) packet router

host

Any device on a TCP/IP network that has an Internet Protocol (IP) address. Examples of hosts include servers, workstations, network-interface print devices, and routers. Sometimes used to refer to a specific network computer that is running a service used by network or remote clients. For Network Load Balancing, a cluster consists of multiple hosts connected over a local area network (LAN).

See also: client cluster local area network (LAN) Network Load Balancing server service Transmission Control Protocol/Internet Protocol (TCP/IP)

host domain

The domain in which a DFS namespace has been configured.

host ID

The portion of the IP address that identifies a computer within a particular network ID.

host name

The DNS name of a device on a network. These names are used to locate computers on the network. To find another computer, its host name must either appear in the Hosts file or be known by a DNS server. For most Windows-based computers, the host name and the computer name are the same.

See also: DNS server Domain Name System (DNS)

host priority

For Network Load Balancing, a host`s precedence for handling default network traffic for TCP and UDP ports. It is used if a host within the cluster goes offline, and it determines which host within the cluster will assume responsibility for the traffic previously handled by the offline host.

See also: cluster host Network Load Balancing User Datagram Protocol (UDP)

host server

The server on which a root target is located.

Hosts file

A local text file in the same format as the 4.3 Berkeley Software Distribution (BSD) UNIX /etc/hosts file. This file maps host names to IP addresses, and it is stored in the \%Systemroot%\System32\Drivers\Etc folder.

HTML

See other term: Hypertext Markup Language (HTML)

HTTP

See other term: Hypertext Transfer Protocol (HTTP)

HTTPS

See other term: Secure Hypertext Transfer Protocol

hub

A common connection point for devices in a network. Typically used to connect segments of a local area network (LAN), a hub contains multiple ports. When data arrives at one port, it is copied to the other ports so that all segments of the LAN can see the data.

See also: local area network (LAN) port switching hub

hubbed mode

A mode in which the Address Resolution Protocol/multicast address resolution service (ARP/MARS) provides asynchronous transfer mode (ATM) addresses to requesting clients in the form of a multicast server (MCS) list value. In this mode, ARP/MARS acts as a multicast server, providing active forwarding of all multicast and broadcast traffic destined for IP addresses contained within the ranges specified in the list.

See also: Address Resolution Protocol (ARP) asynchronous transfer mode (ATM) IP address multicast address resolution service (MARS) multicast server (MCS) nonhubbed mode

hue

The position of a color along the color spectrum. For example, green is between yellow and blue. This attribute can be set using Display in Control Panel.

Hypertext Markup Language (HTML)

A simple markup language used to create hypertext documents that are portable from one platform to another. HTML files are simple ASCII text files with codes embedded (indicated by markup tags) to denote formatting and hypertext links.

See also: American Standard Code for Information Interchange (ASCII)

Hypertext Transfer Protocol (HTTP)

The protocol used to transfer information on the World Wide Web. An HTTP address (one kind of Uniform Resource Locator (URL)) takes the following form: https://www.microsoft.com.

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