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Registration Data Access Protocol

On 17 May 2018 the ICANN Board adopted a Temporary Specification for gTLD Registration Data. This page is under review and will be updated to address the Temporary Specification.

The Registration Data Access Protocol (RDAP) enables users to access current registration data and 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 Pilot Program

An RDAP pilot program, which will conclude on 31 July 2018, is now underway. This voluntary program was initiated at the request [PDF, 93 KB] of the ICANN gTLD Registries Stakeholder Group, with the support of the Registrar Stakeholder Group.

The primary goal of the pilot program is to develop a baseline profile (or profiles) to guide implementation, establish an implementation target date, and develop a plan for the implementation of an RDAP-based solution. To participate in the RDAP pilot program, follow the instructions in the community wiki workspace.

About RDAP

Some of RDAP's advantages over WHOIS protocol include:

  • Standardized query, response and error messages.
  • Secure access to data (i.e., over HTTPS).
  • Extensibility (e.g., makes it easy to add output elements).
  • A bootstrapping mechanism that makes it easy to find the authoritative server for a given query.
  • Redirection/reference mechanism (e.g., from a thin registry to a registrar).
  • Builds on top of the well-known web protocol HTTP.
  • Internationalization support for registration data.
  • Provides the option to enable differentiated access (e.g., limited access for anonymous users and full access for authenticated users).


  • 2017
    • On 1 August, the gTLD Registries Stakeholder Group with support from the Registrar Stakeholder Group submits a proposal to the ICANN organization to implement RDAP with a first phase in the form of an RDAP pilot.
    • On 1 September, the ICANN organization accepts [PDF, 538 KB] the proposal to implement RDAP and starts the first phase: an RDAP pilot.
  • 2016
    • On 26 July, ICANN publishes a gTLD RDAP profile. However, the gTLD Registries Stakeholder Group requests ICANN to not use that profile and instead work together on a modified plan to implement RDAP.
  • 2015
  • 2012
    • On 4 June, ICANN issues a roadmap to implement SAC 051.
    • The WEIRDS working group within the IETF begins developing the Registration Data Access Protocol.
  • 2011
    • On 19 September, the Security and Stability Advisory Committee issues SAC 051 [PDF, 236 KB], which advises the ICANN community to evaluate and adopt a replacement for the existing domain name registration data access protocol (WHOIS).
    • On 28 October, the ICANN Board adopts SAC 051.
  • 2010
    • The ICANN community holds discussions about the need for technical evolution of the WHOIS service.
  • 1982
    • The IETF issued a protocol for a directory service for ARPANET users. This protocol has been in use ever since; it is referred to as WHOIS.
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"""" is not an IDN."