Historical TLDs
A .nato was added in the late 1980s by the NIC for the use of NATO, who felt that none of the then existing TLDs adequately reflected their status as an international organization. Soon after this addition, however, the NIC created the .int TLD for the use of international organizations, and convinced NATO to use nato.int instead. However, the nato TLD, although no longer used, was not deleted until July 1996.

Other historical TLDs are .cs for Czechoslovakia (now .cz for Czech Republic and .sk for Slovak Republic), .zr for Zaire (now .cd for Democratic Republic of the Congo), .oz for Australia (now .au) and .dd for the German Democratic Republic (now .de for Germany). In contrast to these, the TLD .su has remained in active use despite the demise of the Soviet Union that it represents, though .ru is most commonly used for Russian domains.


Reserved TLDs

RFC 2606 reserves the following four top-level domain names for various purposes, with the intention that these should never become actual TLDs in the global DNS:

* .example — reserved for use in examples
* .invalid — reserved for use in obviously invalid domain names
* .localhost — reserved to avoid conflict with the traditional use of localhost
* .test — reserved for use in tests