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RDAP Overview

RDAP Overview
Resources for RDAP Implementers
gTLD RDAP Profile
RDAP Pilot Program
Information for Users

RDAP Overview

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 is a protocol that delivers registration data like WHOIS, but its implementation will change and standardize data access and query response formats. RDAP has several advantages over the WHOIS protocol, including support for internationalization, secure access to data, and the ability to provide differentiated access to registration data.

gTLD RDAP Profile

The ICANN organization worked with a discussion group of generic top-level domain (gTLD)registries and registrars to create a gTLD RDAP profile. The profile, which follows the requirements of the Temporary Specification for gTLD registration data, aims to provide technical instructions to gTLD registries and registrars on how to implement an RDAP service in a consistent way.


gTLD registries and registrars are required to implement an RDAP service by 26 August 2019. ICANN org continues to work with gTLD registries and registrars to implement a service-level agreement and registry reporting requirements for RDAP.

Learn more about the RDAP background here.


Related information and additional resources can be found here:

  • Resources for RDAP implementers

    This page provides tools and resources for ICANN contracted parties who will be implementing an RDAP service.

  • Information for RDAP Users

    This page provides guidance for Internet users seeking a greater understanding of the capabilities supported by RDAP.

  • FAQs

    This page provides answers to frequently asked questions concerning RDAP development and implementation.

  • RDAP pilot

    A group of RDAP implementers is participating in a pilot program to develop upcoming features of the gTLD RDAP services. This page describes the group's work and how to participate.

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."