Nicname (also known as "WhoIs") is a subsystem for the DNS protocol IANA servers operated by ICANN (Internet Corporation for Assigned Names and Numbers). While the IANA DNS servers store the actual IANA Domain Name translation tables; ICANN Nicname servers store the unobscured human-readable database of IANA Domain Name leasee information, including contact information and lease period, provided by the IANA Registrar (a potential privacy issue). Servers are accessed using a TelNet client.

ICANN, while the ultimate authority, has sold rights to specific organizations to manage their portion of the TLD registration and collect a management fee from leasees. These organizations operate Authoritive servers (including sometimes mirrored servers) where they keep the master database for each TLD under their jurisdiction. In order to make locating data easier, a number of Universities and other organizations operate their own Aggregating servers, which combine the databases from each of these authoritive servers together into a single database. There can however be a significant delay from when the Authoritive server posts data to when the Aggregating server updates its database from the Authoritive server. Below are addresses to both Authoritive and Aggregating public IANA Nicname servers.
[IANA Port assignment = 43]