You can get a list of the current root Nameservers (about 10) via anonymous ftp by retrieving netinfo/root-server.txt from ftp://ftp.rs.internic.net/.
Companies accredited by the Internet Corporation for Assigned Names and Numbers (ICANN) are authorized to register .com, .net and .org names in the registry. Here is an alphabetical list of such companies. The largest and most well-know is Network Solutions,NSI. For some time NSI had the sole authority to register domain names in the .com, .org and .net domains (which account for 50-75% of the Internet's addresses). The US government granted NSI this authority in order to transition out of direct government involvement in the process. During this time, Network Solutions became virtually synonomous with the generic term, InterNIC. However now, the registration process has been opened up to competition. NSI still maintains the directoy at the heart of the Internet's domain name system and other centralized functions. (Do they handle .edu, .gov and .mil registrations?)
The .com, .net, and .org domains are available for registration by Internet users across the globe, but ICANN-accredited domain name registrars are also located in various countries around the world. Two letter domains, such as .uk, .de and .jp (for example), are called country code top level domains (ccTLDs) and correspond to a country, territory, or other geographic location. The rules and policies for registering domain names in the ccTLDs vary significantly and some are reserved for use by citizens of the corresponding country. Here is a list of domain name registrars by country.
ICANN has been working to add new top level domains to the Internet domain name system. Some examples are .biz for businesses and .name for individuals. Many of these new top level domains are operational and registrations are being accepted. Domain Name Supporting Organization of ICANN (DNSO) oversees such additions of top level domains. Here is a white paper discussing how the new gTLDs were chosen.
Most types of trademark-based domain-name disputes must be resolved by agreement, court action, or arbitration before a registrar will cancel, suspend, or transfer a domain name. Disputes alleged to arise from abusive registrations of domain names (for example, cybersquatting) may be addressed by expedited administrative proceedings that the holder of trademark rights initiates by filing a complaint with an approved dispute-resolution service provider. Information of ICANN's Uniform Dispute Resolution Policy is available here .
IP address space is distributed in a hierarchical way. The IANA allocates blocks of IP address space to Regional Internet Registries, that allocate blocks of IP address space to their Local Internet Registries, who assign the addresses to end users. There are currently three Regional Internet Registries: 1) Riseaux IP Europiens Network Coordination Centre ( RIPE NCC ) which handles Europe, the Middle East and parts of Africa. 2) American Registry for Internet Numbers ( ARIN ) which handles North and South America, the Caribbean and sub-Saharan Africa . 3) Asia Pacific Network Information Centre ( APNIC ) which handles Asia and the Pacific.
Continued operation of the Internet depends, in part, upon the conservation and efficient use of IP address space. These three regional registries are responsible for promoting the conservation of IP address space, maintaining impartiality while determining the size of address blocks to be allocated or assigned, and supporting efforts to keep the global routing tables to a manageable size to ensure routability of information over the Internet. Here is an example of ARIN's policies on the allocation of blocks of IP addresses. Notice that most hosts get their IP address from an upstream provider and not directly from one of these regional registries (why is this important?).
IPv4 address space is a scarce resource. IPv6 is designed, in part, to alleviate this problem.See also http://moat.nlanr.net/.
Online versions (fewer features than command line versions):
nslookup ,
dig ,
whois
Note: whois does not use the DNS protocol; it uses its own protocol (telnet server whois), but the information it returns is related.