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RDAP is the modern protocol for looking up domain registration records; WHOIS is the older system for similar information. For generic top-level domains (gTLDs), RDAP became ICANN’s definitive source on 28 January 2025. To check a domain, open ICANN Lookup, enter its name, and review the registration record. Some personal details may be hidden or redacted.
What are RDAP and WHOIS?
RDAP stands for Registration Data Access Protocol. It is a protocol—a set of rules that lets lookup software query registration-data services—not a particular website. WHOIS is pronounced “who is”; it is not an acronym. The Internet Engineering Task Force developed RDAP as a replacement for WHOIS, according to ICANN’s RDAP overview.
Both systems can provide information associated with a domain registration. The difference is in how a client finds the relevant service and how the result is delivered. Traditional WHOIS queries typically target a particular registry or registrar database. RDAP supports discovery of authoritative servers and uses standardized query and response formats, with support for internationalization and secure, differentiated access. Those features make results more consistent to process; they do not ensure that every record contains the same public fields.
How to check a domain with ICANN Lookup
- Open ICANN Lookup.
- Enter the domain name in the search field and submit the query.
- Review the returned registration record. Depending on the domain and information published, it may show registrar details, registration or expiration events, status information, and nameservers.
- For repeatable or scripted queries, consider ICANN’s open-source RDAP command-line client; its guidance describes the client and the browser-based tool at ICANN’s RDAP user information page.
ICANN describes its browser client as free to use and says it runs RDAP queries directly from the user’s browser. ICANN estimated in December 2024 that RDAP servers of all types handled more than 10 billion queries per month; that is a dated estimate, not a current 2026 count.
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RDAP versus WHOIS for domain lookups
| Aspect | RDAP | WHOIS |
|---|---|---|
| How the service is found | Supports bootstrap discovery to route a query toward an authoritative server for the registration. | Traditionally queries a specific registry or registrar database. |
| Response format | Standardized query and response formats make results more consistent for software to process. | Older WHOIS services do not provide the same standardized response structure. |
| Current ICANN gTLD status | Definitive source for gTLD registration information since 28 January 2025. | gTLD registries and registrars are generally no longer required to provide WHOIS from that date, with exceptions for .com, .name, and .post. |
| Coverage beyond gTLDs | Support and practices vary; the cited ICANN transition does not establish coverage for every country-code TLD. | Availability and practices likewise depend on the relevant extension and its registry. |
ICANN announced the gTLD transition on 27 January 2025, stating that RDAP would become the definitive source on 28 January. This applies to gTLD registration information, not automatically to every country-code domain. For a particular country-code extension, check the relevant registry’s current lookup guidance.
What a domain lookup can—and cannot—tell you
A lookup displays registration information supplied through registry and registrar services. It is not proof that a website is safe, that a registrant’s identity has been independently verified, or that the domain is available to register. ICANN says it is not responsible for profile content or for verifying user details.
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Some contact information may be absent, masked, or redacted. ICANN’s Registration Data Policy FAQ says redaction is mandatory when needed to comply with applicable law; that does not mean every field must be hidden in every case. A privacy or proxy service may also affect what appears. A blank field alone does not show that the domain has no registrant or that the lookup failed.
What to do if registration details are not public
- Check the public record in ICANN Lookup first.
- If nonpublic gTLD registration information is still needed, check whether the registrar participates in ICANN’s Registration Data Request Service (RDRS). ICANN’s guidance is available at RDRS.
- If RDRS is not available for the registrar, consult the sponsoring registrar’s own disclosure process and follow its current requirements.
RDRS is voluntary, and a request is not a guarantee of access. The registrar’s applicable process determines how a request is handled. ICANN’s Registration Data Policy FAQ, dated 21 August 2025, says the policy took effect that day and explains that contracted parties handle and redact registration data according to the policy and applicable legal requirements. For a specific disclosure request, follow the relevant registrar’s current instructions.
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