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Discussion Paper on Retiring Country Code Top-Level Domains

5 de diciembre de 2006

Contenido disponible solo en los siguientes idiomas

  • English

The Internet Assigned Numbers Authority (IANA), a function performed by ICANN in accordance with its obligations under contract with the U.S. Government, is responsible for the delegation of top-level domains in the DNS root.

IANA relies upon the ISO 3166-1 standard, and specifically the alpha-2 codes contained therein, for definition of two-letter codes that may be used for country-code top-level domains (ccTLDs). IANA allocates ccTLD operators based upon their ability to meet delegation criteria, which includes the ability to demonstrate local support, and technical competency requirements.

Whilst this practice is relatively straightforward for the establishment and ongoing operation of assigned codes, IANA has no formally defined process on how to decommission a country-code top-level domain when it is retired from the “officially assigned” state in the ISO 3166 database.

To date, in the case where a code has been replaced by one or more new codes, IANA has advised the relevant operators that the old code would need to be retired and that they should develop plans to do so1. However, IANA has not aggressively pursued the affected operators to conclude the decommissioning process.

IANA is seeking to review its practices associated with top-level domains which have been revoked from the officially assigned list, and more specifically, top-level domains which have been replaced by a new country code.

A select list of ISO 3166-1 alterations that help illustrate the dimension of the issue are:

  1. Zaire's ("ZR") renaming to the Democratic Republic of the Congo ("CD").

  2. The breakup of the Soviet Union resulting in the code "SU" being replaced with codes for the independent states, such as "RU", "BY", and "UA". Every former soviet state has a new code, which been allocated to an operator by IANA.

  3. East Timor's code changing from "TP" to "TL".

  4. Czechoslovakia’s ("CS") division into the Czech Republic ("CZ") and Slovakia ("SK").

  5. The remaining components of Yugoslavia ("YU") becoming Serbia and Montenegro ("CS"). Following a referendum, in September 2006 Serbia and Montenegro further split into two independent identities Serbia (“RS”) and Montenegro (“ME”).

The ISO 3166 standard also has codes which are "exceptionally reserved", in essence meaning they are special allocations that may be used under certain circumstances. In that category, IANA presently has delegations for three of these codes:

  • The United Kingdom ("GB") have elected to use the exceptionally reserved code of UK as its primary ccTLD.

  • The European Union have been delegated the exceptionally reserved code of EU.

  • Ascension Island is delegated the exceptionally reserved code of AC.

Whilst IANA has overseen the successful transition of "ZR" to "CD", domains such as "SU" and "TP" still exist in the DNS root.

Some of the relevant issues to consider:

  • In the event a code is not revoked in a timely manner, there is a risk that its continued use would deprive its new user of a valid country code should it be reallocated. This is highlighted by the case of "CS", which served Czechoslovakia, and later Serbia and Montenegro.

  • Broadly speaking, each country or autonomous territory has a single top-level domain at their disposal. It may be considered inequitable that certain countries have more than one such domain available. This is highlighted by East Timor (TP and TL) and the United Kingdom (GB and UK), although it should be noted that GB is effectively inactive.

  • The global policy surrounding the operation of ccTLDs heavily emphasises the role of the local Internet community, local government, and local law. Should a code represent an area that does not align to a present-day country, the matter of which government and law has jurisdiction becomes unclear.

With these issues in mind, we are seeking community input on how IANA should handle top-level domains that are no longer ordinarily assigned codes in the ISO-3166.

Guiding questions:

  1. Should IANA adhere to the ISO-3166 standard and remove top-level domains from the DNS root that become transitionally reserved (i.e. retired)?

  2. If so, by what process should this be conducted?

  3. What implementation timeframes for removal should be specified?

  4. If removal is test-based, what specific milestones should signify removal from the root zone?

  5. What pre-emptive right, if any, should existing operators have toward a new code that covers an area previously serviced (in whole, or in part) by another code?

  6. In the event there is more than one code for a particular country available for its use (e.g. GB and UK), what policy should govern their status?

IANA appreciates any and all comments on this issue. Responses either to the questions posed, or the issue in general, can be submitted by sending email to Comments will be viewable at

The comment period will be open until 31 January 2007. At the conclusion of this comment period, a staff report on the comments and a recommended operating procedure will be developed.

Further Reading:


1 The ICANN Board resolution to delegate .TL during its January 2005 meeting specifically calls for the migration of domains from .TP to .TL. ICANN made public statements during 2003 that the .SU domain would be decommissioned, with an estimated time-frame of one year. ICANN staff consultations have been conducted with other affected TLD operators.