.dd part of the Federal Republic of Germany, which had already been assigned the ccTLD .de. The ISO 3166-1 code "DD" was withdrawn in 1990. .dd .dd was the assigned country code top-level domain (ccTLD) for the German Democratic Republic (East Germany). It was chosen based on the ISO 3166-1 alpha-2 code for the German Democratic Republic, the letters coming from the German name of the country: '. In accordance with IANA policy, .dd was therefore available to be assigned as the country code top-level domain (ccTLD) for East Germany. However, this was never done, and so .dd was never added
Sponsored top-level domain restricting the eligibility of registrants to use the TLD. Generally speaking, a sponsored TLD is a specialized TLD that has a sponsor representing the narrower community that is most affected by the TLD, while an unsponsored TLD operates under policies established by the global Internet community directly through the ICANN process. For example, the .aero TLD is sponsored by SITA, which limits registrations to members of the air transport industry. There will be many more of these, including top domains named after and controlled by a company. See Proposed top-level domain and ICANN-era gTLDs. As of 2015, IANA distinguishes the