Network Terms "H"

Network Glossary and acronym's

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

HAL (Hardware Abstraction Layer)

Software that makes it easy for operating systems to interact with different types of hardware.

Hard disk

A magnetic storage device used to store computer data. Workstation computers and servers both have hard disks.

Hardware Abstraction Layer (HAL)

Software that makes it easy for operating systems to interact with different types of hardware.

Hardware Compatibility List (HCL)

A list of hardware devices that have been tested by Microsoft and are known to be compatible with Windows 2000.

Hardware profile

A registry entry that lists the physical devices and services on your computer that Windows 2000 should enable on startup. Profiles can be created for computers that alternate between two or more hardware configurations.

Hashing algorithms

Hashing algorithms are used to create a message digest to ensure that data integrity is maintained. A sender creates a message digest by performing the hash function on the data files to be transmitted. The receiver performs the same action on the data received and compares the two message digests. If they are the same then the data was not altered.

HCL (Hardware Compatibility List)

A list of hardware devices that have been tested by Microsoft and are known to be compatible with Windows 2000.

Header

The header is the initial section of an IPM which contains addressing and routing information for the e-mail message.

Hello PDU

A Hello PDU; such as End System Hello (ESH), Intermediate System Hello (ISH), or IS to IS Hello (IIH); establishes and maintain adjacencies.

Heterogenous

A network that consists of many foreign TCP/IP-based hosts is known as a heterogeneous environment. TCP/IP provides the protocol to connect many foreign computer systems, because each system uses the same protocol.

Hierarchical Storage Management (HSM)

Hierarchical Storage Management (HSM) monitors the way data is used, then automatically moves data between high- and low-cost storage media in a way that will maximize storage utilization. The bulk of an organization's data is kept on slower devices, then a copy of that data is transferred to faster disk drives when needed. This process optimizes utilization by allowing the high-speed disk drives to act as caches for the slower mass storage devices.

High-level formatting

A logical formatting process that prepares the disk to be used by a specific file system. It scans the disk and marks bad sectors, creates the partition boot sector, modifies the partition table on the hard disk, creates the File Allocation Table for FAT volumes, and creates the Master File Table for NTFS volumes.

High-water mark

A server's highest local USN value for which another server has received updates. For example, if Server2 has received updates from Server1 up to Server1's local USN value 4653, then 4653 is Server2's high-water mark for Server1.

Hives

Sections of the Registry made up of keys, subkeys, and values, which are saved as files on your hard disk.

H-node

A protocol used to support NetBIOS over TCP/IP. It is a combination of the p-node and b-node. The default function of an h-node is a P-node. If it cannot resolve a name through the NetBIOS name server, it uses a broadcast to resolve the name.

Hold time

The hold time is the amount of time that a neighbor is considered to be functioning properly without a router receiving a packet from the neighbor.

Hold-down method

With the hold-down method, routers will, for a period of time, "hold" an update that reinstates an expired link. The time period typically reflects the time required to attain convergence on the network. The hold-down timer is reset when the timer runs out or when a network change occurs.

Home directory

A designated folder that is accessible to the user and can contain his or her files and programs. The home directory is assigned in Active Directory Users and Computers or Local Users and Groups and can be assigned to one user or shared by many.

Hop

A hop is a stage on an electronic message's journey from sender to receiver.

Host headers

Alternative names that differentiate multiple Web sites hosted on the same Microsoft Internet Information Server computer. You can allow Web sites to use the same IP address and port number by configuring a unique host header for each site.

Host IDs

An identifier of a workstation, server, router, or other TCP/IP host within a segment. The network ID must be unique to the network ID.

Host name

An alias assigned to a computer by an administrator to identify a TCP/IP host. The host name can be any 256-character string. Multiple host names can be assigned to the same host. Many utilities can use host names rather than the TCP/IP address. A host name always corresponds to an IP address that is stored in a HOSTS file or in a database on a DNS or NetBIOS name server.

Host name resolution

The process of mapping TCP/IP host names to IP addresses.

HOSTS file

A local text file in the same format as the 4.3 Berkeley Software Distribution (BSD) UNIX\etc\host file that maps host names to IP addresses. This file is used to resolve host names for TCP/IP utilities.

Hot Site

A hot site is a fault tolerant strategy which provides a redundant work location. If a disaster renders a work site unusable, the effected organization may have a hot site in which to relocate. Hot sites have the following characteristics:

This is a fully configured facility with power, A/C, etc., fully functional servers and clients that are up-to-date mirroring the production system.
A hot site is immediately available in the event of a disaster.
The site is expensive to maintain; requires constant maintenance of the hardware, software, data, and applications; and presents a security risk.
This facility is necessary when an organization cannot tolerate any downtime.

Hot Spare

A hot spare is a component that is connected to a system. A hot spare can take over automatically when another component fails.

Hot Swap

A component that is hot-swappable can be removed and replaced while the system is still running.

HSM (Hierarchical Storage Management)

HTML (Hypertext Markup Language)

A series of rules for formatting documents that you can transfer between platforms. It is the language used to format ASCII text files as pages for the World Wide Web.

HTTP (Hypertext Transfer Protocol)

The standard protocol for Internet browsing. Using the Hypertext Transfer Protocol (HTTP) with Exchange lets both users and anonymous users access mailboxes, public folders, and address lists by typing the Exchange server's URL into an Internet browser.

HTTPS (Hypertext Transfer Protocol over Secure Socket Layer)

HTTPS is a secure form of HTTP that uses SSL as a sublayer for security.

Hub

A network device that ties multiple workstations (or other devices) together for communication on a network. A hub can come with 5 ports or more and is basically a repeater of data. Also called a multi-port repeater.

Hub Transport server

The Hub Transport server is responsible for handling all message delivery in Exchange 2007.

Hyperlink

A word, phrase, or graphic formatted so that clicking it allows you to display data from another file on your computer, the network, or the Internet.

Hypertext Markup Language (HTML)

A series of rules for formatting documents that you can transfer between platforms. It is the language used to format ASCII text files as pages for the World Wide Web.

Hypertext Transfer Protocol (HTTP)

Hypertext Transfer Protocol over Secure Socket Layer (HTTPS)

HTTPS is a secure form of HTTP that uses SSL as a sublayer for security.