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Evolution of WHOIS Protocol to RDAP - What You Need to Know

Rdap evolution 750x425 23oct19 en

The WHOIS protocol, or Port 43, has been the standard to access domain name registration data for more than 35 years. For most of ICANN's existence, the community has discussed issues related to registration data (or in ICANN-speak, Registration Data Directory Services, or RDDS) and over time identified limitations with the existing technology. These limitations include:

  • No standardized format.
  • Lack of support for internationalization.
  • Inability to authenticate users.
  • Lookup-only abilities and no search support.
  • Lack of standardized redirection or reference.
  • No standardized way of knowing what server to query.
  • Inability to authenticate the server or encrypt data between the server and client.

The Registration Data Access Protocol, known as RDAP, was created by the technical community in the Internet Engineering Task Force (IETF) as an eventual replacement for the WHOIS protocol. RDAP enables users to access current registration data and was designed to help address the limitations of the WHOIS protocol. As we shared in February 2019, the ICANN organization took another important step in a multi-phased approach to transition WHOIS services to RDAP by mandating that all generic top-level domain (gTLD) registries and ICANN-accredited registrars provide RDDS over RDAP in addition to WHOIS by 26 August 2019. We are now well underway with the first step of registrars and registry operators executing the technical implementation of RDAP.

The next step is to amend the current Registry Agreement (RA) and Registrar Accreditation Agreement (RAA) to incorporate contractual requirements comparable to the WHOIS services for RDAP, such as Service Level Agreements, or SLAs. We have initiated negotiations with the gTLD Registries Stakeholder Group and the Registrars Stakeholder Group to begin this process and to define a coordinated transition from the WHOIS protocol to RDAP. ICANN will continue to communicate progress on the amendments and the transition from WHOIS to RDAP, including the plans to raise global awareness of what's changing with the introduction of RDAP, in the coming months.

Port 43 WHOIS protocol users can learn more about RDAP at ICANN66 in Montréal, Canada. Remote participation is available for those who cannot attend in person. Additional resources and information about RDAP can be found at the RDAP webpage.

We look forward to taking these next steps and want to thank the members of the contracted parties community for their participation, support, and contributions during this transition.


    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."