Glossary · ENCheck a domain

RDAP

RDAP (the Registration Data Access Protocol) is a standard way for a lookup tool to request structured information about a registered domain and receive a machine-readable response. A person usually uses RDAP through a website or app; the tool finds the right RDAP server, sends a request, and presents the returned details in a readable form.

What can an RDAP lookup show?

A domain response can include information about the registration, its nameservers, and related parties such as the registrar or registrant. It may also show dates and domain registration status. The exact fields depend on the registry, the registrar, and what may be disclosed. Contact details can be redacted, and a response with missing details does not mean that the registration has no contact information.

For example, Lee enters lee-garden.example in an RDAP-based lookup page. The page returns the registrar, an expiration date, and two nameservers, while the registrant email is withheld. RDAP delivered the structured response; the lookup page chose how to display it. Lee can use the registrar name to find whom to contact, but cannot infer the hidden email address from the result.

How does the request work?

RDAP uses ordinary web-style requests over HTTP. The standard defines a path for looking up a domain name, such as /domain/lee-garden.example, and a response format based on JSON, a common way to represent structured data. The person using a lookup page does not need to type this path or read the raw JSON: the client does that work.

RDAP also lets software identify data fields and response types consistently. This makes it easier for different lookup tools to interpret responses than if every server used unrelated text labels. It supports internationalized domain names and can limit access or show different information to different users where the service requires it. These capabilities do not mean that every server returns every field or that private details become public.

How is RDAP different from WHOIS?

WHOIS is the older query protocol commonly used for registration lookups. Its responses are usually unstructured text, while RDAP defines structured JSON responses and standard query patterns. RDAP was designed to address limits in WHOIS, including inconsistent command and response formats, support for different languages and writing systems, and control over who can access information.

For generic top-level domain (gTLD) registration information, ICANN made RDAP the definitive source starting 28 January 2025, replacing WHOIS services being retired for that purpose. This is an ICANN policy change for gTLDs; other domain endings and registry systems may have different lookup arrangements. A lookup result from either system is about registration records, not proof that a website or email service is online.

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