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Information for RDAP Users

The Registration Data Access Protocol (RDAP) enables users to access domain name registration data. It was created as an eventual replacement for the WHOIS protocol. RDAP was developed by the technical community in the Internet Engineering Task Force (IETF).

RDAP is a protocol that delivers registration data like WHOIS, but its implementation will change and standardize data access and query response formats.

In the short term, RDAP will not replace web-based WHOIS. Based on current policies and agreements, ICANN accredited registrars and gTLD registries will be required to implement RDAP in addition to port 43 WHOIS and web-based WHOIS.

RDAP is a new protocol for accessing registration data in a structured way. In its basic form, it is not intended to offer a "human-friendly" view like most websites would. However, the structure allows additional services to be built on top. ICANN org has set up a website that uses RDAP and presents the registration data in a "human-friendly" way.

Try it!

ICANN's prototype RDAP web client.

These RDAP clients support domain name queries to registries and registrars with RDAP servers. Please note that inclusion of these links does not constitute or imply ICANN's endorsement or recommendation. Please contact the external sites for answers to questions regarding their content.

For further information, contact Global Support.

Domain Name System
Internationalized Domain Name ,IDN,"IDNs are domain names that include characters used in the local representation of languages that are not written with the twenty-six letters of the basic Latin alphabet ""a-z"". An IDN can contain Latin letters with diacritical marks, as required by many European languages, or may consist of characters from non-Latin scripts such as Arabic or Chinese. Many languages also use other types of digits than the European ""0-9"". The basic Latin alphabet together with the European-Arabic digits are, for the purpose of domain names, termed ""ASCII characters"" (ASCII = American Standard Code for Information Interchange). These are also included in the broader range of ""Unicode characters"" that provides the basis for IDNs. The ""hostname rule"" requires that all domain names of the type under consideration here are stored in the DNS using only the ASCII characters listed above, with the one further addition of the hyphen ""-"". The Unicode form of an IDN therefore requires special encoding before it is entered into the DNS. The following terminology is used when distinguishing between these forms: A domain name consists of a series of ""labels"" (separated by ""dots""). The ASCII form of an IDN label is termed an ""A-label"". All operations defined in the DNS protocol use A-labels exclusively. The Unicode form, which a user expects to be displayed, is termed a ""U-label"". The difference may be illustrated with the Hindi word for ""test"" — परीका — appearing here as a U-label would (in the Devanagari script). A special form of ""ASCII compatible encoding"" (abbreviated ACE) is applied to this to produce the corresponding A-label: xn--11b5bs1di. A domain name that only includes ASCII letters, digits, and hyphens is termed an ""LDH label"". Although the definitions of A-labels and LDH-labels overlap, a name consisting exclusively of LDH labels, such as""icann.org"" is not an IDN."