| H.323 |
| H.323 is a superset of ITU standards for voice, data and video communication over packet-based networks, and specifies how terminal devices should communicate with each other in the IP environment. H.323 is designed to ensure the availability of a guaranteed level of service for multimedia communication over LANs. The standard set is to some extent derived from the H.320 multimedia standard for ISDN. It ensures the interoperability of products from different manufacturers. There are four main groups: Terminals, Gateways, Gatekeepers and Multi Control Units (MCU). |
| Hacker |
| A slang term for a computer enthusiast. Among professional programmers, the term hacker implies an amateur or a programmer who lacks formal training. Depending on how it used, the term can be either complimentary or derogatory, although it is developing an increasingly derogatory connotation. The pejorative sense of hacker is becoming more prominent largely because the popular press has coopted the term to refer to individuals who gain unauthorized access to computer systems for the purpose of stealing and corrupting data. Hackers, themselves, maintain that the proper term for such individuals is cracker. |
| Hacking |
| Unauthorized use, or attempts to circumvent or bypass the security mechanisms of an information system or network. |
| Harvest |
| An obsolete NSA computer system used to monitor telegraph traffic. |
| High Availability |
| A system or network design protocol and associated implementation that ensures a high level of operation continuity during a given period of time. Availability refers to the ability of the user community to access the system. Availabilty is usually expressed as a percentage of uptime in a given year. It is the number of minutes of downtime divided by the total minutes in a year (approximately 525,000). 99.9% = 8.76 hours / year 99.99% = 52.6 minutes / year 99.999% = 5.26 minutes / year |
| History Log |
| Stored by the UNIX shell, this log keeps an entry track of recent commands entered by the user. |
| Hoax |
| In virus terms, an email that warns of an invalid viral infection or risk, causing more concern than necessary to the user. |
| Hole |
| A gap in system memory that is unallocated and unused. More casually, a hole is any means by which an intrusion may occur. |
| Hop |
| An intermediate connection in a string of connections linking two network devices. On the Internet, for example, most data packets need to go through several routers before they reach their final destination. Each time the packet is forwarded to the next router, a hop occurs. The more hops, the longer it takes for data to go from source to destination. You can see how many hops it takes to get to another Internet host by using the PING or traceroute utilities. |
| Host Table |
| Used to look up a hostname, which is translated into a corresponding IP address. |
| Host/hosting |
| The host is a networked computer offering resources that a subscriber can access as a guest. An Internet host is therefore a computer that offers data for web users. Hosting is when service providers make space available to their customers on computers that are linked to the network. |
| Hostname |
| On the Internet, the name used to locate a host's IP-address. |
| Hostname Command |
| A command that determines the hostname of a computer, as opposed to only determining an IP address number. |
| HP-UX |
| A version of the UNIX operating system developed by Hewlett-Packard. |
| HTML |
| Short for HyperText Markup Language, the authoring language used to create documents on the World Wide Web. HTML is similar to SGML, although it is not a strict subset. HTML defines the formatting commands, by using a variety of tags and attributes, that create hypertext documents known as Web pages. |
| HTTP |
| Hypertext Transfer Protocol - the set of rules for transferring files on the World Wide Web. HTTP is an application protocol built on the TCP/IP protocols. |
| Hyperlink |
| A text or graphics items on a WWW page that is highlighted in some way, and which calls up another document when it is clicked. It is often simply called a link. |
| Hypertext |
| Hypertext is the basic concept behind the World Wide Web. A text contains references (hyperlinks) to other sources, which can be accessed by clicking on these hyperlinks. Hypertext is defined by HTML on the Internet. |
