IP Address Definitions

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Common terms, definitions, and acronyms for IP address terminology.

The following is a list of definitions and short explanations for some commonly-used terms and acronyms on this site. Many of these terms refer to Internet and networking-related functions and protocols with which some may not be familiar.


American Registry for Internet Numbers. A Regional Internet Registry (RIR) that manages IP address space allocation, transfer, and record maintenance, DNS, among other Internet related functions. The ARIN service region includes Canada, many Caribbean and North Atlantic islands, and the United States.


Address Resolution Protocol. A network protocol that is used to convert an IP addresses to physical addresses or MAC addresses. The protocol operates using a request and reply functionality and operates within a solitary network.


Country-Code Top Level Domain. An Internet top-level domain generally used or reserved for a country, a sovereign state, or a dependent territory. Every two-letter TLD is or originated as a ccTLD, including the recently public domains .co and .me.


Dynamic Host Configuration Protocol. A network protocol used to allow devices on a network to communicate via Internet Protocol (IP). DHCP is used by most routers, and enables connected devices on the network to operate simultaneously while connected to the Internet.


Domain Name System or Domain Name Service. The method of converting human-readable domain names to IP addresses.


DNS-based Blackhole List. A list of IP addresses and domains that have been identified by malicious by one or more sources. The list provides security at the DNS level, providing an additional barrier of security for end-users.


Dynamic Domain Name System/Service. DNS that is configured to periodically update without user intervention or maintenance. This provides static IP address functionality for dynamic IP addressing.


File Transfer Protocol. A network protocol that is used to transfer files over a network, such as the Internet. The default port for FTP is port 21 for most machines. One drawback to FTP is security, which is listed in RFC 2577.


Generic Top-Level Domain. A type of top-level domain that is open for use for any purpose. gTLDs are maintained by the Internet Assigned Numbers Authority (IANA) for use in the DNS of the Internet.


Hyper Text Transfer Protocol. The network protocol that is the foundation of data communication for the World Wide Web. The default port for HTTP is port 80.


Internet Assigned Numbers Authority. IANA is responsible for IP addressing and other Internet protocol resources.


Institute of Electrical and Electronics Engineers. Pronounced “Eye-triple-E,” this organization is a technical community involving Internet professionals from around the world collaborating to promote technological advancement.


Internet Corporation for Assigned Names and Numbers. ICANN coordinates IANA functions as they pertain to the Domain Name System (DNS).


Internet Engineering Task Force. “The goal of the IETF is to make the Internet work better.” The IETF maintains documents that govern protocols and methods of organization on the Internet.


Internet Message Access Protocol. IMAP is a protocol for e-mail retrieval. IMAP allows an e-mail client to access e-mail on a remote mail server. An example of IMAP functionality includes the ability of a smart phone to access one’s email from a built-in mail application.


Internet Protocol.


Internet Protocol Version 4. The fourth version of the Internet Protocol and the first of the IP versions to become widely used.


Internet Protocol Version 6.The sixth version of the Internet Protocol, created to address the shortage in IP addresses under IPv4.


Internet Service Provider. A communications company that offers Internet connectivity as a service to consumers and businesses.


Local Area Network.


Media Access Control. A 48-bit address used to identify a network interface controller.


Multipurpose Internet Mail Extensions.


Network Interface Controller. A piece of hardware that provides an interface for electronic devices to connect to a network. Examples include a wireless network card or Ethernet controller.


Name Server. A server responsible for maintaining DNS records, which point IP addresses to distinct domain names.


Peer to Peer. A networking model that involves the sharing of data or information across multiple clients.


Post Office Protocol.


An application-specific or process-specific connection to a network.


Reverse Domain Name System. The resolution of IP addresses to domain names.


Request for Comments. Memorandums published and maintained by the Internet Engineering Task Force (IETF). RFCs are simply “technical and organizational notes about the Internet”. The RFCs contain information about many aspects of computer networking. Some aspects of networking that are recorded include protocols, procedures, programs, and concepts.


Simple Mail Transport Protocol. See RFC 2821 – IETF.


A list of websites that have appeared in unsolicited messages, or SPAM.


Transmission Control Protocol.


Top-Level Domain


User Datagram Protocol.


Virtual Local Area Network


Virtual Private Network


Wide Area Network


Owner information of a domain name.


World Wide Web.