Domain name

In the Internet, a domain name is a string that identifies a realm of administrative autonomy, authority or control.

Below these top-level domains in the DNS hierarchy are the second-level and third-level domain names that are typically open for reservation by end-users who wish to connect local area networks to the Internet, create other publicly accessible Internet resources or run websites, such as "wikipedia.org".

Domain names are also used as simple identification labels to indicate ownership or control of a resource.

This abstraction allows any resource to be moved to a different physical location in the address topology of the network, globally or locally in an intranet.

The practice of using a simple memorable abstraction of a host's numerical address on a computer network dates back to the ARPANET era, before the advent of today's commercial Internet.

A domain name consists of one or more parts, technically called labels, that are conventionally concatenated, and delimited by dots, such as example.com.

In addition, a group of seven generic top-level domains (gTLD) was implemented which represented a set of categories of names and multi-organizations.

The Internet Assigned Numbers Authority (IANA) maintains an annotated list of top-level domains in the DNS root zone database.

[16] For special purposes, such as network testing, documentation, and other applications, IANA also reserves a set of special-use domain names.

ICANN approved the Internationalized domain name (IDNA) system, which maps Unicode strings used in application user interfaces into the valid DNS character set by an encoding called Punycode.

In addition to ICANN, each top-level domain (TLD) is maintained and serviced technically by an administrative organization operating a registry.

ICANN publishes the complete list of TLD registries and domain name registrars.

Registrant information associated with domain names is maintained in an online database accessible with the WHOIS protocol.

Some domain name registries, often called network information centers (NIC), also function as registrars to end-users.

The registrants (users of a domain name) are customers of the registrar, in some cases through additional layers of resellers.

There are also a few other alternative DNS root providers that try to compete or complement ICANN's role of domain name administration, however, most of them failed to receive wide recognition, and thus domain names offered by those alternative roots cannot be used universally on most other internet-connecting machines without additional dedicated configurations.

A few companies have offered low-cost, below-cost or even free domain registration with a variety of models adopted to recoup the costs to the provider.

In such situations, the proper meaning may be clarified by placement of hyphens when registering a domain name.

For instance, Experts Exchange, a programmers' discussion site, used expertsexchange.com, but changed its domain name to experts-exchange.com.

[29] The domain name is a component of a uniform resource locator (URL) used to access websites, for example: A domain name may point to multiple IP addresses to provide server redundancy for the services offered, a feature that is used to manage the traffic of large, popular websites.

For example, at a public meeting with VeriSign to air technical concerns about Site Finder,[30] numerous people, active in the IETF and other technical bodies, explained how they were surprised by VeriSign's changing the fundamental behavior of a major component of Internet infrastructure, not having obtained the customary consensus.

The original VeriSign implementation broke this assumption for mail, because it would always resolve an erroneous domain name to that of Site Finder.

This was a significant issue in the attempt to create a .xxx top-level domain and sparked greater interest in alternative DNS roots that would be beyond the control of any single country.

[33] In the United States, the Truth in Domain Names Act of 2003, in combination with the PROTECT Act of 2003, forbids the use of a misleading domain name with the intention of attracting Internet users into visiting Internet pornography sites.

Consumer Electronics Association vice president Michael Petricone was worried that seizure was a blunt instrument that could harm legitimate businesses.

[36][37] After a joint operation on February 15, 2011, the DOJ and the Department of Homeland Security claimed to have seized ten domains of websites involved in advertising and distributing child pornography, but also mistakenly seized the domain name of a large DNS provider, temporarily replacing 84,000 websites with seizure notices.

[39] PIPCU and other UK law enforcement organisations make domain suspension requests to Nominet which they process on the basis of breach of terms and conditions.

Domain names used in works of fiction have often been registered in the DNS, either by their creators or by cybersquatters attempting to profit from it.

Misspelled domain names are often used for malicious purposes, such as phishing scams or distributing malware.

[48] Although website and email spoofing attacks are more widely known, any service that relies on domain name resolution may be compromised.