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WHOIS Primer

This WHOIS Primer summarizes the key components of the WHOIS service, policy, and protocols. It takes into account the many contracts, specifications, standards, protocols, advisories, and policies that collectively describe the ICANN WHOIS program applicable to the collection, display, and use of gTLD domain name registration data.

This Primer is based on the obligations described in the 2013 Registrar Accreditation Agreement (2013 RAA), and the base new gTLD Registry Agreement (New GTLD Registry Agreement [PDF, 649 KB]), and in a few instances other registry agreements, as noted below. As not all registrars and registries are operating under the 2013 RAA or the New gTLD Base Agreement, their actual obligations pertaining to WHOIS may vary. Please refer to the language of the original documents for the text of the obligations related to WHOIS.

Introduction to WHOIS

Based on existing consensus policies and contracts, ICANN is committed to "implementing measures to maintain timely, unrestricted and public access to accurate and complete WHOIS information", subject to applicable laws. The WHOIS service is a free, publicly available directory containing the contact and technical information of registered domain name registrants. Anyone who needs to know who is behind a website domain name can make a request for that information via WHOIS. The data is collected and made available by registrars and registries under the terms of their agreements with ICANN.

WHOIS is not a single, centrally managed database. Rather, registration data is held in disparate locations and administered by multiple registries and registrars. They set their own conventions for WHOIS service, consistent with the minimum requirements established in their contracts with ICANN.

The term "WHOIS" refers to protocols, services, and data types associated with Internet naming and numbering resources beyond domain names, such as Internet Protocol (IP) addresses, and Autonomous System Numbers (ASNs). The WHOIS service includes WHOIS clients, WHOIS servers, WHOIS data stores, and WHOIS data (domain name registration records). Essentially, WHOIS can refer to any of the following:

  1. The information that is collected at the time of registration of a domain name or IP numbering resource and subsequently made available via the WHOIS Service, and potentially updated throughout the life of the resource;
  2. The WHOIS Protocol itself, which is defined in RFC 3912; or
  3. The WHOIS Services that provide public access to domain name registration information typically via applications that implement the WHOIS protocol or a web-based interface.

These ambiguities inherent in the WHOIS label complicate efforts to shape the evolution of meta-data for Internet naming and numbering. To address this, ICANN has developed more precise terminology for gTLDs, including:

Domain Name Registration Data (DNRD) – refers to the information that domain name registrants provide when registering a domain name and that registrars or registries collect. Some of this information is made available to the public. For interactions between ICANN accredited Generic Top Level Domain (gTLD) registrars and domain name registrants, the data elements are specified in the current registry agreement and Registrar Accreditation Agreement. For country code Top Level Domains (ccTLDs), the operators of these TLDs implement local policy regarding the request and display of registration information.

Domain Name Registration Data Access Protocol (DNRD-AP) – refers to the elements of a (standard) communications exchange—queries and responses—that make access to registration data possible. For example, the WHOIS protocol (RFC 3912) and Hypertext Transfer Protocol (HTTP) (RFC 2616 and its updates) are commonly used to provide public access [PDF, 649 KB] to DNRD.

Domain Name Registration Data Directory Service (DNRD-DS) – refers to the service(s) offered by registries and registrars to provide access to (potentially a subset of) the DNRD. This term is now often used interchangeably with Registration Directory Service (RDS).

Uses of WHOIS

Internet operators use WHOIS to identify individuals or entities responsible for the operation of a network resource on the Internet. Over time, WHOIS has evolved to serve the need of many different stakeholders, such as domain name registrants, law enforcement agents, intellectual property and trademark owners, businesses and individuals.

Stakeholders use the WHOIS service for a variety of purposes, including to:

  • Determine whether a domain is available
  • Contact network administrators regarding technical matters
  • Diagnose registration difficulties
  • Contact web administrators for resolution of technical matters associated with a domain name
  • Obtain the real world identity, business location and contact information of an online merchant or business, or generally, any organization that has an online presence
  • Associate a company, organization, or individual with a domain name, and to identify the party that is operating a web or other publicly accessible service using a domain name, for commercial or other purposes
  • Contact a domain name registrant for the purpose of discussing and negotiating a secondary market transaction related to a registered domain name
  • Notify a domain name registrant of the registrant's obligation to maintain accurate registration information
  • Contact a domain name registrant on matters related to the protection and enforcement of intellectual property rights
  • Establish or look into an identity in cyberspace, and as part of an incident response following an Internet or computer attack- (Security professionals and law enforcement agents use WHOIS to identify points of contact for a domain name)
  • Gather investigative leads (i.e., to identify parties from whom additional information might be obtained)- Law enforcement agents use WHOIS to find email addresses and attempt to identify the location of an alleged perpetrator of a crime involving fraud
  • Investigate spam- law enforcement agents look to the WHOIS database to collect information on the website advertised in the spam

Under the ICANN contracts, WHOIS can be used for any legal purpose except to enable mass unsolicited, commercial advertising or solicitations, or to enable high volume, automated, electronic processes that send queries or data to a registry or registrar's systems, except as necessary to manage domain names.

WHOIS Requirements

Anyone wishing to register a domain name must provide contact and technical information for display in the WHOIS database; WHOIS data is actually a subset of the information due at the time of registration.

In turn, ICANN's agreements with registrars require them to provide public access to data on registered names. The 2013 RAA states that "at its expense, Registrar shall provide an interactive web page and, with respect to any gTLD operating a "thin" registry, a port 43 WHOIS service (each accessible via both IPv4 and IPv6) providing free public query-based access to up-to-date (i.e., updated at least daily) data concerning all active Registered Names sponsored by Registrar in any gTLD."

For the generic top-level domain (gTLD) registries, ICANN specifies WHOIS service requirements through the registry agreements [PDF, 649 KB]. Registries satisfy their WHOIS obligations using different data models. The two common models are often characterized as "thin" and "thick" WHOIS registries. Although the new "thick" WHOIS policy now requires all new gTLD registries operate a thick registry, currently a few existing registries (such as .COM and .NET) have not yet transitioned to "thick" WHOIS and still operate a thin registry. A thin registry only includes data sufficient to identify the sponsoring registrar, status of the registration, creation and expiration dates for each registration, name server data, and last time the record is updated in its WHOIS data store. Thick registries maintain the domain name registrant's contact information and designated administrative and technical contact information, in addition to the sponsoring registrar and registration status information supplied by a thin registry.

Additionally, domain name registrants are required to provide timely updates (within seven days) to WHOIS data for a registered domain name. The registrar is then obligated to promptly update the WHOIS data.


Because registration data connects individuals or organizations with domain names, domain name registrants are required to provide accurate and reliable contact details. If the domain name registrant knowingly provides inaccurate information, fails to update information within seven days of any change, or does not respond within 15 days to an inquiry about accuracy, the domain name may be suspended or cancelled.

For their part, registrars are required to comply with the new WHOIS Accuracy Specification. They must verify certain WHOIS fields such as email addresses or phone numbers and validate the presence of data as well as the format of email addresses, postal addresses and telephone numbers. Registrars are also obliged to send annual data reminder notices to domain name registrants and to verify and validate changes to WHOIS data.

Registrars are obligated to perform these validation and verifications of these WHOIS data fields within fifteen days of the domain registration, inter-registrar transfer, or any change in the domain name registrant. However, if a registrar has already successfully completed the validation and verification procedures on the identical contact information, and is not in possession of facts or knowledge of circumstances that suggest that the information is no longer valid, then it is not obligated to re-validate or re-verify these WHOIS data fields.

Anyone can submit complaints of inaccuracies through ICANN organization's WHOIS data reporting system, and the RAA requires registrars to investigate claims of inaccuracy. Registrars must also re-verify and re-validate certain WHOIS data fields if they have any information suggesting that these WHOIS data fields are incorrect.

In order to verify and ensure the operational stability of registry services, as well as to facilitate compliance checks on accredited registrars, registries provide ICANN with weekly, specific up-to-date thin registration data [PDF, 649 KB]. Registries also are required [PDF, 649 KB] in exceptional cases, such as failure of a registry, to provide bulk access to thick registration data to ICANN.


Registrars and registries [PDF, 649 KB] are obligated to provide access to WHOIS data through registration data publication services. It must be publicly available in a specific format and on a designated "port" reserved for WHOIS data sharing (port 43), as well as on an interactive webpage. Port 43 access by registrars is required only for domain names registered in 'thin' registries. The data must include specific identification, contact and technical information.

At present, web-based WHOIS queries may be performed through the websites of ICANN organization itself, ICANN accredited registrars and registries, most regional Internet registries, and third party WHOIS client providers. The agreement between a gTLD registry operator and registrar may, if approved by ICANN organization in writing, state alternative requirements for that gTLD. Also, under certain market conditions, the registrar may be obligated to provide bulk access to WHOIS.

Data available depends on whether a registry is "thick" or "thin". Only a few registries that existed prior to the new gTLD program are "thin," (such as .com and .net). Thin registries do not include domain name registrant contact details. For thin registries, registrars provide the specific domain name registrant contact information.

ICANN specifies Service Level Agreements related to the performance and acceptable downtime of the registrar & registry's [PDF, 649 KB] WHOIS services. This includes downtime for maintenance, planned outages or system failures, and performance response times to Internet user queries.

Anyone can submit a complaint that a registrar's WHOIS service is down. Registries must submit monthly WHOIS performance reports to ICANN organization.

Reseller Related Obligations

To the extent that a reseller is involved in facilitating a registration of a domain name, registrars must enter into written agreements with all of its resellers that enable the registrar to comply with and perform all of its obligations.

Obligations of Licensors of Domain Names

Licensors of domain names also have responsibility for the actions of licensees. Any domain name registrant that licenses use of a domain name to a third party is responsible for providing its own full contact information and for providing and updating accurate technical and administrative contact information adequate to facilitate timely resolution of any problems that arise in connection with the registered domain name. A domain name registrant licensing use of a domain name is liable for harm caused by wrongful use of the domain name, unless it discloses the current contact information provided by the licensee and the identity of the licensee within seven (7) days to a party providing the domain name registrant reasonable evidence of actionable harm.

Data Escrow

ICANN requires registrars to submit an electronic copy of the registrar's database, which includes WHOIS data, to a reputable escrow agent on a schedule, under the terms, and in the format specified by ICANN.

Registries are required [PDF, 649 KB] to deposit domain name registration data, along with other registry data, in escrow, with an escrow agent.

Centralized WHOIS

The RAA specifies that if the WHOIS service implemented by registrars does not provide reliable and convenient access to accurate and up-to-date data, ICANN may set up centralized access to remote data.

In response to the WHOIS Review Team's recommendations, ICANN has committed to creating a centralized look-up tool that will interface with the WHOIS databases of registrars and registries to simplify and make the WHOIS service more convenient for its users.

Data Elements

The format of responses must contain certain data elements and follow a semi-free text format. A list of the available data elements and directions about which ones are required/mandatory is included in the Registration Data Directory Services Specification to the 2013 RAA.

There are also specific formatting requirements for registrars and registries [PDF, 649 KB], such as those specified by the Registry Registration Data Directory Services Consistent Labeling and Display Policy.

Internationalized Registration Data

Earlier WHOIS specifications did not include language or script requirements for input or output. Implementation efforts are now underway to internationalize WHOIS, in accordance with the new Translation and Transliteration of Contact Information Policy.

Searchability Features

Registries have the option to provide certain search functionality [PDF, 649 KB] for the WHOIS.

Privacy Considerations

Registrars must notify each new or renewed domain name registrant as to the purpose of the personal data collected. The domain name registrant must also consent to the data processing.

Registrars and registries must comply with applicable laws and government regulations regarding the collection, display and distribution of personal data via WHOIS. If a registrar or registry encounters a conflict with local laws, ICANN has procedures in place for reviewing and considering those situations, including processes for requesting a WHOIS data retention specification waiver.

Privacy / Proxy Services

Privacy and proxy services are for individuals and entities who wish to keep certain information from being made public via WHOIS.

There are two general types of these services:

  • A "Privacy Service" lists alternative, reliable contact information, like an address or phone number, in WHOIS while keeping the domain name registered to its beneficial user as the domain name registrant.
  • A Proxy Service registers the domain name itself and licenses use of the domain name to its customer. The contact information of the service provider is displayed rather than the customer's contact information. The proxy service is responsible for providing accurate contact information adequate to facilitate timely resolution of any problems that arise in connection with the domain name.

Privacy and proxy services offered by registrars or their affiliates are subject to additional obligations. These privacy and proxy providers must disclose their Service Terms, publish an Abuse of Point Contact and meet Escrow Obligations. Further issues associated with privacy and proxy service accreditation are currently being addressed through implementation of new policies.

Educating Domain Name Registrants about WHOIS

Registrars and registries [PDF, 649 KB] must provide domain name registrants certain WHOIS policy and educational information – for example, by reference to this website and WHOIS Primer.

Benefits and Responsibilities Documents

Every registrar must publish on its website(s) and/or provide a link to the Domain Name Registrants' Benefits and Responsibilities Specification.

Domain name registrants' rights include:

Instructions that explain the registrar's processes for registering, managing, transferring, renewing, and restoring domain name registrations, including through any proxy or privacy services made available by the registrar.

Domain Name Registrants' Responsibilities include:

Providing accurate information for publication in directories such as WHOIS, and promptly update the data to reflect any changes.

WHOIS in Domain Name Management and Dispute Resolution Procedures

WHOIS is referenced to conduct specific functions related to the operation of domain names. For example, WHOIS is used to support the transfer or deletion of a domain name, or to facilitate trademark related administrative dispute resolution proceedings such as the Uniform Dispute Resolution Policy (UDRP) and the Uniform Rapid Suspension System (URS).


Under the ICANN Policy on transfers between registrars, the authority to transfer a domain name is restricted to the administrative contact and the domain name registrant in the WHOIS record. The gaining registrar must obtain a valid Form of Authorization (FOA) from either of these contacts.

If the transfer between registrars is contentious, the Registrar Transfer Dispute Policy allows a registry to examine the WHOIS evidence to determine if the transfer was properly authorized.


Sometimes domain name registrations are deleted – such as in the case of false contact data or non-response to a registrar's inquiries. Under the Expired Domain Name Recovery Policy, the domain name registrant at expiration in the WHOIS record is offered a Redemption Grace Period of 30 days to request the restoration of a domain name. During this time, the registered domain name is disabled and cannot be transferred.

Under the Restored Names Accuracy Policy, following the restoration of the domain name, the domain name registration must be placed on hold until updated and accurate WHOIS information is provided.

Uniform Dispute Resolution Policy (UDRP)

Under the rules for the UDRP, the WHOIS record is referenced to:

  • Identify the domain name registrant to be named in a UDRP Complaint as the respondent.
  • Determine appropriate jurisdiction for any court proceedings related to a UDRP case.
  • Determine whether the registrar has properly "locked" the domain name registration. Once a UDRP complaint is received, the registrar must "lock" the domain name registration to prevent any transfers as long as the complaint proceeding is pending.

New gTLD Uniform Rapid Suspension System (URS)

WHOIS is also referenced in trademark related complaints in new gTLDs under the Uniform Rapid Suspension System (URS) to:

  • Identify the domain name registrant to be named in a URS Complaint as the respondent.
  • Confirm URS Locking: upon initiation of a complaint, a Notice of Complaint is sent by the URS provider to the addresses listed in the WHOIS contact information that provides an electronic copy of the complaint, advises of the locked status, as well as the potential effects if the domain name registrant fails to respond and defend against the complaint.
  • Notice of Default: If there is a default decision, a notice of default is sent to the addresses listed in the WHOIS.
  • Confirm a URS suspension: the WHOIS record is updated to reflect that the domain name may not be transferred, deleted or modified.

Updating or Modifying ICANN’S WHOIS Program

Changes to WHOIS can occur in a variety of ways. ICANN's Bylaws require periodic reviews to assess the effectiveness of the current gTLD Registration Directory Service (RDS, formerly known as WHOIS), and those reviews can lead to modifications of the WHOIS Program. Changes to WHOIS obligations can also be accomplished through the contract amendment clauses in the RAA and in each of the Registry Agreements. In addition, consensus policies created through recommendations developed by the Generic Names Supporting Organization (GNSO) as approved by the Board in accordance with the procedures under the ICANN Bylaws, can also change WHOIS obligations. For example, a GNSO Policy Development Process is now underway to identify requirements for Registration Directory Services and make a recommendation as to whether a next-generation WHOIS replacement is needed to meet those requirements.


This summary is not intended to be comprehensive, but illustrative of the breadth of the WHOIS program. Please refer to actual contract terms, specifications, and policies for the definitive obligations. ICANN organization has posted a "Single Webpage for ICANN WHOIS-Related Policies and Provisions" as a resource to identify the location of these obligations. As noted above, this WHOIS Primer is based on the terms of the 2013 RAA and the New gTLD Base Agreement. Not all registrars or registries are bound by these form agreements, and as a result, the WHOIS obligations may vary from registry to registry, and from registrar to registrar, depending upon what version of RAA registrar is under. Please visit the accredited registrar listing to identify the contract version applicable to specific registrars.

Last Updated: July 2017