.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 The ISO 3166-1 code "DD" was withdrawn in 1990.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
Top-level domain the Internet Assigned Numbers Authority (IANA), and is in charge of maintaining the DNS root zone. IANA currently distinguishes the following groups of top-level domains: domain (.arpa) Originally, the top-level domain space was organized into three main groups: "Countries", "Categories", and "Multiorganizations". An additional "temporary" group consisted of only the initial DNS domain, arpa, and was intended for transitional purposes toward the stabilization of the domain name system. As of 2015, IANA distinguishes the following groups of top-level domains: Countries are designated in the Domain Name System by their two-letter ISO country code; there are exceptions, however (e.g., .uk). This