Pseudo top-level domain
Encyclopedia
A number of pseudo-top-level domains to be used in naming computers have been defined at various times. These "pseudo-TLDs" or "pseudomains" include .bitnet
, .csnet
, .exit, .i2p, .local
, .onion
, .oz
, .freenet
and .uucp
. Although these pseudo-TLDs look like top-level domain
s, and serve the same syntactic function in creating names for network endpoints, they have no meaning in the global Domain Name System
and are (or were) used only for specialist purposes; typically for addressing machines that were not reachable via the Internet Protocol
for use in services such as E-mail
and Usenet
via UUCP
.
Although they have no official status, they are generally regarded as having been unofficially "grandfathered", and are unlikely ever to be allocated as top-level domains. A peculiar case is .root, as it might appear to "exist".
.bitnet
.bitnet was a pseudo-domain-style suffix used in the late 1980s when identifying a hostname not connected directly to the Internet but possibly reachable through inter-network gateways. In this case, it indicated that the hostname preceding it was reachable via the BITNET network...
, .csnet
.csnet
.csnet is a hostname suffix that was used for identifying nodes in the Computer Science Network not directly connected to the Internet but reachable through special gateway systems. It was never installed as a top-level domain in the Domain Name System, but parsed in the message routing logic of...
, .exit, .i2p, .local
.local
local is a pseudo-top-level domain used in multicast domain name service of zero configuration networking discovery protocols.Apple's Bonjour implements mDNS, as does Avahi...
, .onion
.onion
.onion is a pseudo-top-level domain host suffix designating an anonymous hidden service reachable via the Tor network...
, .oz
.oz
.oz is a Domain Name System pseudo-top-level domain that is used by MHSnet, the Australian Computer Science Network. .oz domain hosts that are available on the Internet have been migrated to .oz.au...
, .freenet
Freenet
Freenet is a decentralized, censorship-resistant distributed data store originally designed by Ian Clarke. According to Clarke, Freenet aims to provide freedom of speech through a peer-to-peer network with strong protection of anonymity; as part of supporting its users' freedom, Freenet is free and...
and .uucp
.uucp
The name uucp was a pseudo-domain-style suffix used in the 1980s when identifying a hostname not connected directly to the Internet, but possibly reachable through other inter-network gateways...
. Although these pseudo-TLDs look like top-level domain
Top-level domain
A top-level domain is one of the domains at the highest level in the hierarchical Domain Name System of the Internet. The top-level domain names are installed in the root zone of the name space. For all domains in lower levels, it is the last part of the domain name, that is, the last label of a...
s, and serve the same syntactic function in creating names for network endpoints, they have no meaning in the global Domain Name System
Domain name system
The Domain Name System is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities...
and are (or were) used only for specialist purposes; typically for addressing machines that were not reachable via the Internet Protocol
Internet Protocol
The Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...
for use in services such as E-mail
E-mail
Electronic mail, commonly known as email or e-mail, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the...
and Usenet
Usenet
Usenet is a worldwide distributed Internet discussion system. It developed from the general purpose UUCP architecture of the same name.Duke University graduate students Tom Truscott and Jim Ellis conceived the idea in 1979 and it was established in 1980...
via UUCP
UUCP
UUCP is an abbreviation for Unix-to-Unix Copy. The term generally refers to a suite of computer programs and protocols allowing remote execution of commands and transfer of files, email and netnews between computers. Specifically, a command named uucp is one of the programs in the suite; it...
.
Although they have no official status, they are generally regarded as having been unofficially "grandfathered", and are unlikely ever to be allocated as top-level domains. A peculiar case is .root, as it might appear to "exist".