First, the international domain name (international top-level domain-names, short iTDs), also known as the international top-level domain. This is the earliest and most widely used domain name. Industrial and commercial enterprises such as that. Com, said that the network providers. Net, said the non-profit organizations. Org and so on. Second, the domestic domain, also known as the domestic top-level domain (national top-level domainnames, short nTLDs), the distribution according to different countries with different suffix, the domain name shall be the country's national top level domain. Currently more than 200 countries and regions allocated in accordance with ISO3166 country code top level domain, such as China is cn, the United States is us, Japan is jp and so on. Detailed below. In the actual use and function, the international domain names and no difference between the domestic domain, is unique on the Internet identity. Only in the final administration, the international domain name authorized by the U.S. Department of Commerce Internet Corporation for Assigned Names and Numbers (The Internet Corporation for Assigned Names and Numbers) that ICANN is responsible for registration and management; the domestic domain by the China Internet Network Management Centre ( China Internet Network Information Center) that is responsible for registration and management of CNNIC.