For decades, WHOIS was synonymous with looking up information about a domain name. If you wanted to know when a domain was registered, which registrar managed it, when it expired, or who owned it, you performed a WHOIS lookup.
That terminology is so familiar that many domain owners still refer to any domain registration search as a “WHOIS lookup.”
But the system behind domain registration lookups has changed. RDAP, or Registration Data Access Protocol, has replaced WHOIS as the definitive protocol for accessing registration data for generic top-level domains (gTLDs).
The change is significant, but it happened quietly enough that many domain owners may not even realize it.
What Happened to WHOIS?
WHOIS dates back to the early days of the internet. It was designed to provide information about registered internet resources and eventually became the standard method for retrieving domain registration records.
The problem is that WHOIS was developed for a much different internet.
WHOIS responses were primarily text-based and lacked a universally standardized format. Different registrars and registries could return information differently, making the data more difficult for applications to interpret reliably.
There were also limitations involving internationalization, authentication, access controls, and privacy.
RDAP was developed as a modern replacement. On January 28, 2025, RDAP became the definitive source for registration information for generic top-level domains. ICANN ended the contractual requirement for most gTLD registries and registrars to continue providing registration data through the traditional WHOIS protocols.
In practical terms, RDAP is now the modern standard for domain registration lookups.
What Is RDAP?
RDAP stands for Registration Data Access Protocol. Like WHOIS, it allows registration information about internet resources including domain names to be retrieved. The major difference is how that information is delivered.
RDAP was designed specifically for today’s internet and uses web technologies such as HTTPS and structured data.
Instead of receiving a block of loosely formatted WHOIS text, an RDAP request returns structured information that applications can interpret consistently.
For a domain name, that information can include:
- Domain name
- Registrar
- Registrant information when publicly disclosed
- Original registration date
- Expiration date
- Last updated date
- Domain status codes
- Nameservers
- DNSSEC information
- Registry identifiers
The exact information available varies by domain, registry, registrar, and applicable registration-data policies.
RDAP vs. WHOIS
From the user’s perspective, an RDAP lookup and a traditional WHOIS lookup may appear similar. You enter a domain name and receive registration information.
Behind the scenes, however, RDAP is substantially different.
Traditional WHOIS relies on an older query-and-response protocol and commonly returns plain text. RDAP operates over HTTPS and returns structured data, typically JSON.
RDAP also provides a standardized framework for features that were difficult or impossible to implement consistently with traditional WHOIS, including authentication, internationalization, secure web-based access, and differentiated access to registration information.
For developers building domain tools, structured RDAP data is particularly valuable because individual pieces of information can be identified and presented consistently rather than extracted from differently formatted WHOIS responses.
Why Isn’t the Domain Owner’s Name Shown?
This is one of the biggest changes domain owners notice when performing registration lookups today.
Years ago, a WHOIS lookup frequently revealed the registrant’s name, organization, mailing address, telephone number, and email address.
Today, much of that information is often not publicly disclosed.
Privacy laws and changes to domain registration-data policies have significantly changed how personal registration information is made available publicly.
RDAP is capable of providing registrant information. If registrant information is publicly available for a particular domain, an RDAP response can include it.
However, for many domains, a public RDAP lookup will not reveal the identity or personal contact information of the registrant.
That does not mean RDAP failed to find the information or that the lookup service removed it. It means the information was not provided as part of the publicly accessible registration record.
Can You Still Find Out Who Owns a Domain?
Sometimes.
If registrant information is publicly disclosed through RDAP, it may identify a person or organization associated with the domain.
In other cases, the registrar may provide a privacy-protected email address, contact form, or another mechanism for contacting the registrant without publicly revealing their personal information.
This is particularly important when you’re researching a domain that you would like to purchase.
A domain may already be registered but unused, parked, or simply redirecting somewhere else. The lack of publicly available registrant information doesn’t necessarily mean the owner cannot be contacted.
The registrar, domain marketplace, website associated with the domain, historical information, business records, or other sources may provide additional avenues for identifying or contacting the domain holder.
For certain legitimate requests involving nonpublic gTLD registration data, ICANN also operates the Registration Data Request Service (RDRS), which provides a standardized process for submitting requests to participating registrars.
Do WHOIS Lookups Still Exist?
The term certainly does.
“WHOIS” has been associated with domain registration searches for so long that it is unlikely to disappear from everyday use anytime soon.
Many websites may continue calling their tools “WHOIS Lookup” even when the registration information behind those tools is being retrieved through RDAP or another registration-data service.
So when someone says they want to “check the WHOIS” for a domain, what they generally mean today is that they want to see the domain’s registration information.
The technology used to retrieve that information has evolved.
Why RDAP Is an Improvement
For most people simply looking up a domain, the transition from WHOIS to RDAP may not seem dramatic. The end result is still registration information displayed on a screen.
But the underlying improvement is substantial.
RDAP provides a modern, standardized foundation for registration-data services. It uses HTTPS, provides structured responses, supports internationalized data, and was designed with modern security and access requirements in mind.
It also gives developers a much better foundation for building domain research tools.
Instead of trying to interpret inconsistent WHOIS text from different sources, applications can work with predictable, structured registration data.
That should ultimately make domain lookup services more reliable and easier to maintain.
Try a Domain RDAP Lookup
We recently added a Domain Lookup tool to DomainTraders that retrieves publicly available domain registration information using RDAP.
Enter a domain name to see available information including the registrar, registrant disclosure status, registration date, domain age, expiration date, nameservers, DNSSEC information, and registry status codes.
If registrant information is publicly available through RDAP, the lookup can display it. When it isn’t available in the public registration record, the lookup will indicate that the registrant information is not publicly disclosed.
The transition from WHOIS to RDAP may not have received much attention outside the domain industry, but it represents an important modernization of one of the internet’s oldest services.
For domain owners, investors, developers, and anyone researching a domain name, RDAP is the new standard and it’s worth knowing what changed.