Skip to main content


What is RDAP?

The Registration Data Access Protocol (RDAP) is expected to eventually replace the WHOIS protocol. 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.

RDAP functions are fundamentally different from WHOIS. A WHOIS query is limited to the specific database queried, be it a registry operator or registrar's registration data database. By contrast, RDAP also has a functionality known as "bootstrap" that enables a query to go beyond a specific registry operator or registrar to enable a search of all registration data available in the RDAP service. Instead of returning a result such as "not available," a query will route to the authoritative server to return the relevant data. This is different from the current WHOIS protocol, where the information is not linked across contracted party systems. This enables broader searches while at the same time minimizing the amount of data that is routinely transferred from one entity to another.

Why is RDAP being implemented?

Deficiencies with the current WHOIS system, such as lack of support for internationalization, secure access to data, differentiated access, standardized query, response, and error responses, have been recognized for over a decade. ICANN's Security and Stability Advisory Committee advised in 2011 that the ICANN community evaluate and adopt a replacement protocol. SAC 051: SSAC Report on Domain Name Whois Terminology and Structure [PDF, 243 KB].

The Internet Engineering Task Force (IETF) has led the work on a replacement protocol (more information available in Background. The ICANN org has been working with registry operators and registrars on RDAP implementation, most recently through the RDAP pilot program. Registry operators and registrars will be required to implement RDAP under the Temporary Specification for gTLD Registration Data. It is expected that RDAP will also be required under any new policy that will go into effect after the expiration of the Temporary Specification.

Will RDAP replace web-based and port 43 WHOIS?

ICANN-accredited registrars currently must provide access to registration data to the public in two ways:

  • An interactive web page provided on the registrar's website (web-based WHOIS); and
  • WHOIS (port 43) lookup as defined by RFC 3912.

In the short term, RDAP will not replace web-based or port 43 WHOIS. Based on current policies and agreements, contracted parties will be required to implement RDAP in addition to (port 43) WHOIS and web-based WHOIS.

Will RDAP implementation require registry operators or registrars to make any changes to existing registration data?

RDAP implementation will not require changes to the data that is already stored and accessed via WHOIS; it is simply a new way of accessing that registration data.

The registration data is the same, but the structure of the response is different. Having said that, an RDAP client is likely to format the response in a way that is user-friendly and perhaps similar to the WHOIS format, at least at the onset of RDAP deployment.

How will the privacy of registration data be protected in RDAP?

RDAP provides the option to enable differentiated access (for example, limited access for anonymous users and full access for authenticated users).

Under the Temporary Specification, contracted parties are in some cases required or allowed to restrict public access to gTLD registration data. This will also apply in RDAP under the Temporary Specification.

How can a third party access registration data using RDAP?

RDAP is a protocol, not a website an entity can visit to access registration data. RDAP is used using a command line utility, lookup software, or third-party website. ICANN has set up the RDAP Web Client which third parties are free to use.

Are gTLD registries or registrars required to implement RDAP?

Yes, on 27 February 2019, the ICANN org issued a notification to gTLD registries and registrars of the requirement to implement an RDAP service by 26 August 2019. If you are a gTLD registry or registrar, you may want to review our resources for RDAP Implementers.

How do I update the RDAP Base URL for my registrar in RADAR?

From the home "Registrar View" page, click the "RDAP Base URL" button from the list of available options in the right-side menu. Type the new RDAP Base URL in the text field. Click the "Save" button. The window refreshes and returns to "Registrar View".

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"""" is not an IDN."