Note only one “at” or “@” is allowed, and that the domains form a hierarchy with the most general in scope last. And note that the choice of domain names must be administratively controlled and the highest level domain names must be globally unique.
– J. Postel; Computer Mail Meeting Notes, RFC 805; 8 Feb 1982.
In the fall of 1999, ICANN chose a list of accredited domain registrars as alternative suppliers to the original registrar Network Solutions, and now any of these registrars can register a domain name. The actual costs of administering a domain name are very low, and getting lower as technology and bandwidth gets cheaper, so domain registrars compete on cost and extra services. Many support the non-profit group CoreNIC.
Network Solutions has implemented a central registry database that is shared by all the accredited domain registrars, and so, because of their history, Network Solutions still retains a singular responsibility for the operation of the Internet. A range of standards govern this distributed registration system.
Countries. The IANA CCLTD Database maintains a list of the domain registrars for countries. For example, the following sites provide domain name registration services in various country top-level domains.
- Canadian Registration Services — .ca
- Danish NIC — .dk
- DENIC — .de
- Mexican Registration Services — .mx
- UK Domain Registration Services – .uk
Top-level domains. The following sites provide domain name registration services in various other miscellaneous top-level domains.
- Asia-Pacific Network Information Center — APNIC
- American Registry for Internet Numbers — ARIN
- RIPE NCC — Réseaux IP Européens
- US Department of Defence — .mil domain
- US Domain Registration Services — .us domain
- US Government — .gov
Dispute resolution. The WIPO Arbitration and Mediation Center handles disputes over the ownership and registration of domain names.