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gateway
The term "gateway" can have two definitions in the context of networking. 1. A gateway can be a protocol converter. This type of gateway converts data between two distinct types of protocol architectures, often at the higher layers of the OSI model. 2. A gateway can also be a router used to connect a private network to a public network, typically the Internet.
hacker
A hacker is a very skilled, curious, experimental programmer. A hack is an unorthodox, often elegant, solution to a programming problem. See criminal hacker.
half-duplex
See duplex.
handshake
An exchange of signals and data that prepares two devices to communicate with each other is referred to as a handshake.
header
A header is part of a message that contains information necessary to send the message from one node to another. The header normally contains a field specifying the length of the encapsulated message, together with at least one field providing information about the message. If, for example, the message is a segment of a larger message, the header might specify the relative position of the segment in the complete message and probably the total number of segments in the message.
hertz (Hz)
The frequency of an analog signal is measured in cycles per second or Hz. One Hz is 1 cycle per second; 1,000 cycles per second is 1 kHz; and 1 million cycles per second is 1 MHz.
High-Level Data Link Control (HDLC)
HDLC is a Data Link Layer protocol for point-to-point and point-to-multipoint communication. The HDLC protocol suite represents a wide variety of link layer protocols, such as SDLC, LAPB, LAPD, frame relay, and PPP.
host
A host is any computer system that provides a resource over a TCP/IP network. A host may be a PC, UNIX workstation, networking device, or supercomputer.
hub
Also called a wiring concentrator, a simple hub is a repeater with multiple ports. A signal coming into one port is repeated out the other ports.
Hypertext Markup Language (HTML)
HTML is a text-based language used to generically format text for Web pages. HTML tags different parts of a document more in terms of their function than their appearance. A Web browser reads an HTML document and displays it as indicated by the HTML formatting tags and the browser's default settings.
Hypertext Transfer Protocol (HTTP)
HTTP is the Application Layer protocol used to request and transmit HTML documents. HTTP is the underlying protocol of the Web.
Industry Standard Architecture (ISA)
ISA is an older PC bus technology used in IBM XT and AT computers. See bus.
Institute of Electrical and Electronics Engineers (IEEE)
IEEE is a professional organization composed of engineers, scientists, and students. Founded in 1884, IEEE publishes computer and electronics standards, such as the 802 series that defines shared-media networks such as Ethernet and Token Ring.
Integrated Services Digital Network (ISDN)
ISDN is a WAN technology used to move voice and data over the telecommunication network. ISDN operates at speeds of 144 Kbps to 1.5 Mbps.
interexchange carrier (IXC)
An IXC is a long-distance company that provides telephone and data services between LATAs.
International Electrotechnical Commission (IEC)
A voluntary organization, chartered by the United Nations, IEC defines standards for electrical and electronic technologies. ANSI represents the United States in the IEC.
International Standards Organization (ISO)
ISO is a voluntary organization, chartered by the United Nations, that defines international standards for all fields other than electricity and electronics. (IEC handles electricity and electronics standards.) ANSI represents the United States in ISO.
International Telecommunication Union-Telecommunications Standardization Sector (ITU-T)
ITU-T is an intergovernmental organization that develops and adopts international telecommunication standards and treaties. ITU was founded in 1865 and became a United Nations agency in 1947.
Internet
The term Internet, capitalized, refers to the global internetwork of TCP/IP networks.
Internet Protocol (IP)
IP is a Network Layer protocol responsible for getting a packet (datagram) through a network. It is the "IP" in "TCP/IP."
Internet service provider (ISP)
Companies that provide Internet access to individuals and businesses are referred to as ISPs. ISPs typically provide a range of services necessary to provide corporate networks and other users with dedicated or dial-up access to the Internet.
internetwork
A complex network that may combine smaller networks in different physical locations, based on different types of network architectures is referred to as an internetwork.
Internetwork Packet Exchange (IPX)
IPX is Novell NetWare's proprietary Network Layer protocol.
intranet
An intranet is a network that uses Internet applications, but is designed for use only by the personnel of a company or organization; that is, it is a "private internet."
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