What Is RDAP? The Modern Way to Look Up Domain Data

RDAP, the Registration Data Access Protocol, is how you ask a domain registry or registrar for the public facts about a domain name: when it was registered, when it expires, which registrar manages it, which nameservers it uses and what status locks are in place. It was designed to replace the older WHOIS service with something structured, predictable and machine-readable, and for generic top-level domains it is now the definitive source.

The problem RDAP solves

For decades, domain registration data was published over WHOIS, a very simple protocol: you open a connection, send a domain name and receive a block of text. Every registry formatted that text differently, there was no standard way to find the right server, and non-ASCII characters were handled inconsistently. Software that consumed WHOIS output had to rely on fragile, per-registry text parsing.

RDAP keeps the same purpose but fixes the mechanics. Queries are ordinary HTTPS requests, answers are JSON documents with defined fields, and there is an official way to discover which server is responsible for which TLD. A closer comparison is in RDAP vs WHOIS.

The standards behind it

RDAP is an IETF standard defined across several RFCs. The ones you are most likely to see referenced are:

• RFC 9082 – the query format, meaning the URL patterns such as /domain/example.com.
• RFC 9083 – the JSON response format, including objects for domains, nameservers and entities (people and organizations).
• RFC 9224 – bootstrapping, which explains how a client finds the right RDAP server for a given TLD.
• RFC 9537 – how to mark data that has been redacted, so a client can tell "hidden" apart from "not present."

How a lookup works

An RDAP client follows a short sequence:

1. Find the server. IANA publishes a bootstrap file that maps TLDs to the base URLs of their RDAP services. The client looks up the domain's TLD in that file.
2. Send the query. The client requests a URL like https://rdap.example.net/domain/example.com over HTTPS.
3. Parse the response. A found domain returns HTTP 200 with a JSON body. A domain the server has no record of usually returns HTTP 404.
4. Optionally follow a referral. Some registry responses include a link to the registrar's own RDAP service, which may hold additional detail.

A trimmed response looks something like this:

{
  "objectClassName": "domain",
  "ldhName": "example.com",
  "status": ["client transfer prohibited"],
  "events": [
    { "eventAction": "registration", "eventDate": "2015-03-10T14:22:05Z" },
    { "eventAction": "expiration", "eventDate": "2027-03-10T14:22:05Z" },
    { "eventAction": "last changed", "eventDate": "2026-02-01T09:15:40Z" }
  ],
  "nameservers": [
    { "objectClassName": "nameserver", "ldhName": "ns1.example.net" },
    { "objectClassName": "nameserver", "ldhName": "ns2.example.org" }
  ],
  "secureDNS": { "delegationSigned": false }
}

Reading the important fields

Events

The events array holds the dates that matter. registration is when the current registration began, expiration is when the current term ends and last changed records the most recent update to the domain object. You may also see last update of RDAP database, which describes the freshness of the data rather than the domain itself.

Status values

RDAP status values map to the EPP statuses that registries use internally. Common examples:

• active – no special restrictions.
• client transfer prohibited – the registrar has locked the domain against transfers, a normal protective setting.
• server hold or client hold – the domain is not published in DNS, so it will not resolve.
• redemption period or pending delete – the domain has expired and is moving through deletion. See Domain expiry explained.

Entities

Entities are the people and organizations attached to the domain, each with one or more roles such as registrar, registrant, technical or abuse. Contact details are expressed in jCard, a JSON form of the vCard format. The registrar entity often includes its IANA registrar ID and an abuse contact, which is useful when reporting phishing or malware.

Nameservers and DNSSEC

The nameservers list shows the delegation recorded at the registry. The secureDNS object indicates whether the domain is DNSSEC-signed at the parent, sometimes including the DS record data. If this disagrees with what you see in live DNS, that is worth investigating.

Redaction and privacy

Much personal data in registration records is no longer public. Data protection laws, including the GDPR in Europe, led registries and registrars to withhold registrant names, addresses, phone numbers and email addresses for many domains. RDAP handles this more cleanly than WHOIS did: RFC 9537 lets a server say explicitly which fields were redacted and why. A result showing "REDACTED FOR PRIVACY," or a registrant with no contact details, is normal and does not suggest anything is wrong.

RDAP also supports authenticated, differentiated access, so that parties with a legitimate need can in principle see more than anonymous users. Most public lookups, including the ones you run on a website, see only the public view.

What RDAP cannot tell you

• Availability is not guaranteed by a 404. A missing RDAP record usually means the name is not registered, but names can also be reserved by the registry, blocked for policy reasons, held back as premium inventory or otherwise not open for registration. Only a registrar's availability check at the moment of purchase is definitive.
• Not every TLD has RDAP. Generic TLDs are required to provide it, but country-code TLDs set their own policies. Some ccTLDs run RDAP, some offer only WHOIS or a web form, and a few publish nothing machine-readable. See What is a ccTLD?.
• Registry data is not live DNS. RDAP shows what the registry has on file. What resolvers actually return depends on the zone and on caches, which you can check separately with DNS tools.
• Dates reflect the current registration. If a domain was deleted and later registered again, the registration date shows the newer registration, not the first time the name ever existed.

Check it yourself

• RDAP Lookup queries the authoritative RDAP service for a domain and presents status, dates, registrar and nameservers in readable form.
• Domain Availability combines RDAP and DNS signals to give an indication of whether a name is registered, with the limits described above.
• Domain Expiry reads the expiration event and shows how much time remains on the current term.