A
country code top-level domain (
ccTLD) is an
Internet top-level domain generally used or reserved for a
country, a sovereign state, or a
dependent territory.
All ASCII ccTLD identifiers are two letters long, and all two-letter top-level domains are ccTLDs. In 2010, the Internet Assigned Numbers Authority (IANA) began implementing internationalized country code TLDs, consisting of language-native characters when displayed in an end-user application. Creation and delegation of ccTLDs is described in RFC 1591, corresponding to ISO 3166-1 alpha-2 country codes.
Delegation and management
IANA is responsible for determining an appropriate trustee for each ccTLD. Administration and control is then delegated to that trustee, which is responsible for the policies and operation of the domain. The current delegation can be determined from
IANA's list of ccTLDs. Individual ccTLDs may have varying requirements and fees for registering
subdomains. There may be a local presence requirement (for instance, citizenship or other connection to the ccTLD), as for example the
Canadian (
ca) and
German (
de) domains, or registration may be open.
Relation to ISO 3166-1
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Unused ISO 3166-1 codes
Almost all current ISO 3166-1 codes have been assigned and do exist in DNS.
However, some of these are effectively unused. In particular, the ccTLDs for the Norwegian dependency
Bouvet Island (
bv) and the designation
Svalbard and Jan Mayen (
sj) do exist in DNS, but no subdomains have been assigned, and it is
Norid policy not to assign any at present. Two
French territories,
bl (
Saint Barthélemy) and
mf (
Saint Martin), await local assignment by France's government.
The code eh, although eligible as ccTLD for Western Sahara, has never been assigned and does not exist in DNS. Only one subdomain is still registered in gb (ISO 3166-1 for the United Kingdom) and no new registrations are being accepted for it. Sites in the United Kingdom generally use uk (see below).
The former .um ccTLD for the U.S. Minor Outlying Islands was removed in April 2008. Under RFC 1591 rules .um is eligible as a ccTLD on request by the relevant governmental agency and local Internet user community.
ASCII ccTLDs not in ISO 3166-1
Several ASCII ccTLDs are in use that are not ISO 3166-1 two-letter codes. Some of these codes were specified in older versions of the ISO list.
uk (United Kingdom): The ISO 3166-1 code for the United Kingdom is GB. However, the JANET network had already selected uk as a top-level identifier for its pre-existing Name Registration Scheme, and this was incorporated into the DNS root. gb was assigned with the intention of a transition, but this never occurred and the use of uk is now entrenched.
su This obsolete ISO 3166 code for the Soviet Union was assigned when the Soviet Union was still extant; moreover, new su registrations are accepted.
ac (Ascension Island): This code is a vestige of IANA's decision in 1996 to allow the use of codes reserved in the ISO 3166-1 alpha-2 reserve list for use by the Universal Postal Union. The decision was later reversed, with Ascension Island now the sole outlier. (Three other ccTLDs, gg (Guernsey), im (Isle of Man) and je (Jersey) also fell under this category from 1996 until they received corresponding ISO 3166 codes in March 2006.)
eu (European Union): On September 25, 2000, ICANN decided to allow the use of any two-letter code in the ISO 3166-1 reserve list that is reserved for all purposes. Only EU currently meets this criterion. Following a decision by the EU's Council of Telecommunications Ministers in March 2002, progress was slow, but a registry (named EURid) was chosen by the European Commission, and criteria for allocation set: ICANN approved eu as a ccTLD, and it opened for registration on 7 December 2005 for the holders of prior rights. Since 7 April 2006, registration is open to all.
tp (the previous ISO 3166-1 code for East Timor): Being phased out in favor of tl since 2005.
Historical ccTLDs
There are two ccTLDs that have been deleted after the corresponding 2-letter code was withdrawn from ISO 3166-1:
cs (for
Czechoslovakia) and
zr (for
Zaire). There may be a significant delay between withdrawal from ISO 3166-1 and deletion from the DNS; for example, ZR ceased to be an ISO 3166-1 code in 1997, but the
zr ccTLD was not deleted until 2001. Other ccTLDs corresponding to obsolete ISO 3166-1 have not yet been deleted. In some cases they may never be deleted due to the amount of disruption this would cause for a heavily used ccTLD. In particular, the Soviet Union's ccTLD
su remains in use more than a decade after SU was removed from ISO 3166-1.
The historical country codes dd for the German Democratic Republic and yd for South Yemen were eligible for a ccTLD, but not allocated; see also de and ye.
The temporary reassignment of country code CS to Serbia and Montenegro until the split into rs (Serbia) and me (Montenegro), led to some controversies with respect to the stability of ISO 3166-1 country codes, resulting in a second edition of ISO 3166-1 in 2007 with a guarantee that retired codes will not be reassigned for at least 50 years, and the replacement of RFC 3066 by RFC 4646 for country codes used in language tags in 2006.
The previous ISO 3166-1 code for Yugoslavia, YU, was removed by ISO on 2003-07-23, but the yu ccTLD remained in operation. Finally, after a two-year transition to Serbian rs and Montenegrin me, the .yu domain was phased out in March 2010.
Australia was originally assigned the oz country code, which was later changed to au with the .oz domains moved to .oz.au.
Internationalized ccTLDs
An
internationalized country code top-level domain (IDN ccTLD) is a top-level domain with a specially encoded domain name that is displayed in an end user application, such as a
web browser, in its language-native script or
alphabet, such as the
Arabic alphabet, or a non-alphabetic
writing system, such as
Chinese characters. IDN ccTLDs are an application of the
internationalized domain name (IDN) system to top-level Internet domains assigned to countries, or independent geographic regions.
ICANN started to accept applications for IDN ccTLDs in November 2009, and installed the first set into the Domain Names System in May 2010. The first set was a group of Arabic names for the countries of Egypt, Saudi Arabia, and the United Arab Emirates. By May 2010, 21 countries had submitted applications to ICANN, representing 11 languages.
Unconventional usage
Lenient registration restrictions on certain ccTLDs have resulted in domain names like
I.am,
fa.st,
tip.it,
start.at and
go.to. Other variations of ccTLD usage have been called
domain hacks, where the
second-level domain and ccTLD are used together to form one word or one title. This has resulted in domains like
blo.gs of
South Georgia and the South Sandwich Islands (
gs),
del.icio.us of
United States of America (
us), and
cr.yp.to of
Tonga (
to). The
.co domain of Colombia has generated significant interest as a potential competitor to generic TLDs for commercial use given its possible use as the abbreviation for the word "company". In June and July 2010 .co was opened for public registrations.
Unconventional ccTLDs (such as .cm) form speculation over typographical errors. The .cm domain of Cameroon has generated interest due to the possibility that people might miss typing the "o" for sites in the .com domain.
Commercial and vanity use
A number of the world's smallest countries have licensed their TLDs for worldwide commercial use. For example,
Tuvalu and the
Federated States of Micronesia, small island-states in the Pacific, have partnered with
VeriSign and FSM Telecommunications respectively, to sell domain names using the
tv and
fm TLDs to television and radio stations.
Vanity ccTLDs are TLDs which are used for various purposes outside their home countries, because of their name.
For example:
ac (Ascension Island) is sometimes used to stand for "Access Connection" or "Access Card". It is often used by Universities to stand for "Academic".
ad (Andorra) has recently been increasingly used by advertising agencies or classified advertising.
ag (Antigua and Barbuda) is sometimes used for agricultural sites. In Germany and German-speaking countries, AG (short for Aktiengesellschaft) is appended to the name of a stock-based company, similar to Inc. in USA.
am (Armenia) is often used for AM radio stations, or for domain hacks.
as (American Samoa) In Estonia, Denmark and Norway, AS is appended to the name of a stock-based company, similar to Inc. in USA. In Czech Republic, the joint stock corporation a.s. abbreviation stands for Akciová spolecnost.
at (Austria) is used for English words ending in at.
be (Belgium) is sometimes used for the literal term "be" and the Swiss Canton of Bern. It is also used in some download sites as the end of the word "tube" such as downloadyoutu.be, a site for the downloading of youtube videos.
by (Belarus) is sometimes used in Germany, as "BY" is the official abbreviation of the state Bayern.
ca (Canada) is occasionally used to create domain hacks like histori.ca, the web domain of The Historica Dominion Institute. This type of use is limited by the .ca domain's Canadian residence requirements.
cc (Cocos (Keeling) Islands) is used for a wide variety of sites such as community colleges, especially before such institutions were allowed to use .edu.
cd (Democratic Republic of Congo) is used for CD merchants and file sharing sites.
ch (
Switzerland) is used for a number of church websites.
ck (Cook Islands) was notably abused in Chris Morris's Nathan Barley by preceding it with ".co" in order to spell out the word "cock" (.co.ck as in trashbat.co.ck).
co (
Colombia) is marketed as commercial, corporation, or company. and has quickly become one of the most used ccTLDs for vanity. It is used worldwide by individuals, and companies offering services, because of the meaning in English and more languages.
mn (Mongolia) is used to abbreviate Minnesota.
ms (Montserrat) is also used by Microsoft for such projects as popfly.ms.
mu (Mauritius) is used within the music industry.
ni (Nicaragua) is occasionally adopted by companies from Northern Ireland, particularly to distinguish from the more usual .uk within all parts of the United Kingdom.
nu (Niue) is marketed as resembling "new" in English and "now" in Scandinavian/Dutch. Also means "nude" in French and Portuguese.
pr (Puerto Rico) can be used in the meaning of "Public Relations".
rs (Serbia) is marketed in English words ending with the letters "rs" such as www.blogge.rs.
sc (Seychelles) is often used as .Source .
sh (
Saint Helena) is also sometimes used for entities connected to the
German Bundesland of
Schleswig-Holstein or the
Swiss Canton of
Schaffhausen, or to
Shanghai or
Shenzen in China.
si (Slovenia) is also used by Hispanic sites as "yes" ("sí"). Mexican mayor candidate Jorge Arana, for example, had his web site registered as http://www.jorgearana.si (i.e. "Jorge Arana, sí", meaning "Jorge Arana, yes").
sr (
Suriname) is marketed in the USA as being for "seniors".
st (São Tomé and Príncipe) is being marketed worldwide as an abbreviation for various things including "street".
tm (Turkmenistan) can be used as "trade mark".
to (Tonga) is often used as the English word "to", like "go.to"; also is marketed as the TLD for Toronto and for the Italian city and province of Turin (Torino in Italian).
tv (Tuvalu) is used for the television/entertainment industry purposes. It is also used for local businesses in the province of Treviso (Italy).
vc (Saint Vincent and the Grenadines) is sometimes used to abbreviate "Vacation Club" or "Virtual Casino".
vg (British Virgin Islands) is sometimes used to abbreviate Video games.
vu (Vanuatu) means "seen" in French as well as an abbreviation for the English language word "view".
ws (Samoa, earlier Western Samoa) is marketed as .Website.
See also
List of Internet top-level domains
References
External links
IANA's list of TLDs – official site
World Intellectual Property Organization (WIPO) Domain name dispute resolution]
World-Wide Alliance of Top Level Domain-names
Norid: Domain name registries around the world
ccTLD and TLD analysis of several Zone files
The ICANN Country Code Names Supporting Organisation (ccNSO)
Category:Top-level domains
Category:Country codes
Category:Domain name system