[#acriab]: IAB
See Individual Address Block (“IAB”).
[#ianaabbr]: IANA
See: IANA.
[#iab]: Individual Address Block (by IEEE) (“IAB”)
This information has moved. See: IAB for more details. Basically, an IAB is very similar to an OUI-24, but smaller and cheaper.
[#incremnt]: increment

Adding by the exact value of one. So, incrementing the number 15 results in 16. (Going from 15 to 17, through the process of incrementing, would require incrementing twice.) The opposing action is called “decrement”.

[#indsarci]: Industry Standard Architecture (“ISA”)

(Little/unverified info may be in this section.) A series of standards for allowing a motherboard to communicate with peripheral devices. Standards included 8-bit ISA and 16-bit EISA. Vesa Local Bus (VLB) may also have been compatible.

[#infsuphy]: The Information Superhighway

This name referred to the concept of a nationwide computing network that used fiber-optic network connections. Wikipedia's web page about “Information Superhighway” quotes the “McGraw-Hill Computer Desktop Encyclopedia”. Part of that quote states, “The Internet was originally cited as a model for this superhighway; however, with the explosion of the World Wide Web, the Internet became the information superhighway”.


For computer programmers, an instance is basically a copy that exists and which fits certain specifications. The term is often used in reference to objects when object-oriented programming (“OOP”) is used. With OOP, a programmer may make a class (as related to objects). A class is basically the specifications/blueprints/guidelines about what an object will be like. Each time that an object is made according to those specifications, the created object is called an “instance” of the class. The task of creating such an object my be called “instantiation” (pronounced like in-stan-she-a-shun).

The term might also be used similarly in other contexts. For instance, Microsoft Windows may come with a program called Notepad.exe. If there are multiple running copies of the program, each copy could be referred to as an “instance” of Notepad.

[#ieee]: Institute of Electrical and Electronics Engineers (“IEEE”)

This organization is in charge of creating many standards. With computers, some of the most notable standards are those that work with the physical medium. Primary examples definitely include: Ethernet, and Wi-Fi.

See: IEEE.

[#ittcc]: International Telegraph and Telephone Consultative Committee

An old name for what has since become ITU-T. Actually, the official name of the organization, at the time, was the French name. That name was CCITT (Comité Consultatif International Téléphonique et Télégraphique).

[#internet]: Internet/internet

The term “internet” was initially used to the concept of a network that connected to other networks that may be run by different people. So, if IBM had a network that could connect to Microsoft, and Apple had a network that could connect to Novell, then these would be different internets. There was a similar-sounding term, “intranet”, which referred to multiple networks that were run by the same organization. For example, Apple Corporation might have had one intranet used by an accounting department, and another intranet used by a sales department.

One network grew in size, growing larger than all other networks. This network was the global internet, and it was given a name: the Internet. (The “I” is capitalized, because it is a name.)

The exact definition of the “Internet” varied.

The Internet

One definition used is that the Internet contained all the computers which are able to communicate on the global worldwide network using a specific set of rules. These rules were the fourth version of some rules that were named “Internet protocol”, more commonly known as IP.

Two Internets?

In the early twenty-first century (and still true at the time of this writing), some people have made the claim that there were two Internets.

The description mentioned above referred to computers that communicate using the “Internet protocol”. That definition seemed a bit ambiguous, because there was just one widely used “Internet protocol”.

Since that time, another set of rules have been designed to be used for a global network. This newer set of rules was called “IPv6”, which stood for “Internet Protocol Version 6”. Also, in many cases, the phrase “IP” has been renamed to “IPv4”. The phrase “IP” began to refer to both “IPv4” and “IPv6”, which was not a problem in many cases because “IPv4” and “IPv6” do have a lot of similarities.

At the time of this writing (in the year 2014), some people have said there are two Internets: the earlier Internet contains computers that communicate with “IPv4”, and the second Internet contains computers that communicate with “IPv6”. The reason for this distinction is to help make clear that even if computers in France and Australia can communicate with one Internet protocol (like IPv6), that does not necessarily mean that those same computers can communicate with another computer (perhaps in Canada) that uses another Internet protocol (IPv4). Understanding that definition is a useful concept.

The “IPv4 Internet” contains computers and other devices that are able to communicate using the set of rules that are called “IPv4”, and the “IPv6 Internet” contains the (computers and other) devices that are able to communicate using the set of rules that are called “IPv6”. Few experts would disagree at all with that terminology. So, some people would say that if there is an “IPv4 Internet” and an “IPv6 Internet”, then there are two Internets.

In general, it seems that most people who are not heavily into computers think of the term “Internet” as referring to the global network. To clarify, the name “Internet” refers to just one single network, in the minds of most lay people. Since many computers on the public IPv6 Internet can also communicate to the IPv4 Internet, the idea of having two Internets may be a concept that many people consider to be more confusing than beneficial.

Temporary and/or limited connectivity

There are other ambiguities. If someone runs an FTP server, a firewall might prevent incoming network traffic from reaching the FTP server. Network traffic cannot go from the global network called the “Internet” to the FTP server because of technologies such as firewalling, and possibly the effects of a process called “network address translation” (“NAT”). Therefore, the FTP server might not be reachable from the public Internet. However, a cell phone may be used to send an E-Mail to an E-Mail address on the Internet. A person could say that the cell phone was on the Internet to be able to do things like send that E-Mail and to be able to access a web page. The exact problems that prevented the FTP server from communicating were not problems that prevented the cell phone from working. If the computer running the FTP server cannot receive an FTP or HTTP connection, but can send an E-Mail, is that computer on the Internet? Some people might say, “partially”.

So, the following is a fairly good description of the Internet: Devices which are able to communicate on the global worldwide network using a set of rules called “Internet protocol”. However, know that there are some different definitions. Some of those definitions work better in some cases, while other definitions might be more useful than other cases.

See also: information superhighway.

[#iana]: Internet Assigned Numbers Authority (“IANA”)

The organization that oversees the assignment of many crucial numbers including TCP port numbers and UDP port numbers (which redirects to IANA list of service names and related TCP port numbers and UDP port numbers) and protocol numbers and IP addresses. Mostly IP addresses are handled by the RIRs although IANA does keep track of some lists, at least including IANA's list of IPv4 address space assignments, IANA's list of IPv6 address space assignments, IPv6 reserved Multicast addresses and reserved (IPv4) Multicast addresses. IANA also keeps track of many numbers used by some popular/critical protocols, such as ICMPv6 “Parameters” (“message types”) and ICMP (for IPv4) “Parameters” (“message types”).

IANA's parent organization is ICANN, and IANA works closely with the IETF. (Many of the RFC documents published by the IETF make reference to things that IANA should keep track of.)

[#igrp]: Internet Group Management Protocol (“IGMP”)

See the Glossary section for “multicast”, which currently discusses this protocol.

IANA Protocol Numbers, as well as some older RFC's, have reserved protocol number 2 for IGMP. This protocol number is used by the “Protocol” field of IPv4 packets, as well as the “Next Header” field of IPv6 packets. However, this protocol is really only used for IPv4. IPv6 uses a different implementation called Multicast Listener Discovery (“MLD”) which uses specific types of ICMPv6 messages for communication.

There are multiple versions of IGMP. Multicast HowTo section 7.1: IGMP provides some more details about the communications.

Microsoft Windows users may be able to get some information using netsh (see: TechNet guide to netsh routing IP IGMP, Windows XP Pro documentation related to Netsh routing, although that did not seem to work in Win7, so might only be for Windows Server 2008 R2 or newer, or maybe also Windows Server 2008? Or only systems using RRAS?)

Linux-based operating systems might not typically come with software to perform similar functions, but network crafting may be a solution (as indicated by some comments from serverfault.com post about IGMP from the command line referencing “iperf”, or Nemesis (see: manual page (on web format) for nemesis-igmp, packetlevel: information on using nemesis).

[#ipac]: Internet Protocol Automatic Configuration

(Following is info which may need further review)

This is Automatic Private IP Addressing (“APIPA”). For further details, read about RFC 3927: Dynamic Configuration of IPv4 Link-Local Addresses (Appendex A.3) (and Appendex A.4, and the document as a whole) and APIPA.

The rest of this description is about the usage of the name IPAC. According to Q220874: How to use automatic TCP/IP addressing without a DHCP server, “The operating system versions listed in the "Applies to" section of this article have a feature called Automatic Private IP Addressing (APIPA).” In that article, the “APPLIES TO” section lists “Microsoft Windows 98 Standard Edition” and newer operating systems up through Windows Server 2003. So, even though APIPA may be a newer term made after Windows 98's implementation was released, Microsoft does consider that first implementation to be an implementation of APIPA. Online references to the older name or abbreviation include the IPAC_*.INF files referenced in Q188480: Windows 98 Mtsutil.txt File (“README for the MTSutil directory on the Windows 98 CD”) and Q189255: Error message: Invalid DHCP Lease.

[#isp]: Internet Service Provider (“ISP”)

This term refers to any organization providing the service of routing traffic from an end user's device to and from the Internet. The term generally refers to organizations that are providing this service to the general public or, more traditionally, to pre-authorized individuals. Very often these pre-authorized individuals are simply “subscribers” who are members of the general public, but who have signed up for service (and probably need to pay for it).

Giant ISPs include telecommunications companies. Providers of wireless mobile phone service have also allowed Internet traffic. Some local companies have been able to provide such service, possibly by utilizing service provided by a local phone company. Such smaller companies have often provided additional services, including providing E-Mail service, hosting web sites, and handling DNS registrations. More recently, many of the surviving ISPs have been providing some newer technologies such as virtualization or other similar “cloud” services (like online backup?).

[#ipx]: Internetwork Packet Exchange (“IPX”)

(Following is info which may need further review)

This is Novell-created. (Wikipedia's article on IPX/SPX says “IPX and SPX are derived from Xerox Network Systems' IDP and SPP protocols, respectively.” IPX-compatible drivers for many networking cards were provided by vendors. The rest of the IPX/SPX suite would typically be provided by Novell, although Microsoft also included NWLink as part of some versions of Windows (up through Server 2003 but not Vista).

OpenBSD: archive


[#isaabbr] [#isa]: ISA
Industry Standard Architecture

See Industry Standard Architecture.

People who worked with computers before the PCI bus was released, around July of 1993, may be most familiar with the term as referring to Industry Standard Architecture (“ISA”).

Instruction Set Architecture

The set of instructions that are supported by a particular CPU design. Such a CPU design is often called an “architecture”, and is a critical part of what is called the “platform”. (The most significant parts of a “platform” are the details of the hardware architecture, and the details of the software environment (like which operating system is used)).

People with low level hardware details, including programmers of “assembly language”, may be familiar with the abbreviation standing for “instruction set architecture”. This refers to the “instruction set” (which is the list of available commands that are supported; in this case it refers to the commands accepted by a CPU). The term “instruction set architecture” refers to other details as well, like the state of a CPU. It might even be true that people dealing with such specialties actually use that term a fair amount, although the term is not commonly used by many other computer programmers or computer users.

The phrase “instruction set archicture” was probably a less wide-spread use of the term, although the “Industry Standard Architecture” refers to specific technology standards that is no longer used widely. It has now been decades since the Industry Standard Architecture started to fade from widespread usage. Therefore, the phrase “Industry Standard Architecture” might now be used even less commonly than “instruction set architecture”.

Microsoft Internet Security and Acceleration
See: Microsoft Internet Security and Acceleration.
[#iterate]: iterate
e.g.: an “iterative loop”

An “iteration” of a loop refers to a single time that a loop runs. Each time the program performs an “iteration” of the loop, the program “iterates” through the loop.

The “iterative” (or “iterating”) for loop uses a variable, which is called an “iterator”, to keep track of how many times the program has “iterated” through the for loop.

[#ituhypht]: ITU Telecommunication Standardization Sector (“ITU-T”)

Part of the International Telecommunication Union. (For whatever it is worth, Wikipedia's page on E-carrier does reference this name expeanded directly, referring to the organization as “International Telecommunication Union Telecommunication Standardization Sector (ITU-T)”. The ITU portion of the name is a separate hyperlink from the “Telecommunication Standardization Sector” portion of the name.)

Before being a part of a larger organization called ITU, this old organization had other names. The most official name was CCITT (Comité Consultatif International Téléphonique et Télégraphique), although in English they may have been known as “International Telegraph and Telephone Consultative Committee”.

[#igrp]: Interior Gateway Routing Protocol