Whois Checker

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About Whois Checker

Whois Checker gives you access to a database of all domain names registered worldwide. It searches public registration data relating to Internet domains. This data is stored on WHOIS servers all over the globe.

We use Whois Checker for administrative purposes. System support personnel use it to solve domain registration issues for customers. You can use it to find what domain names are available. You can also use it to figure out how to contact the responsible party for a domain.

How Can I Use It?

Type the domain name or URL that you want to investigate into the search box. Enter the text from the image into the Image Verification challenge to verify that you are human. Push the search button to execute your query. Whois Checker will show you whether anyone owns the domain name. It can also show you important details like: 

  • Who owns the domain.
  • How to contact them.
  • When the domain registration expires.
  • When it was first registered.

The range of information available to you depends partly on which regional registry or top-level domain handles the query. For some domains, you will see two sets of WHOIS data, from thin WHOIS and thick WHOIS.

Not all domain registration information is public. If the information is public, you will be able to view it in Whois Checker. If the information is private, Whois Checker will display contact information for an organization which knows how to reach the domain owner. You can pass information to domain owners to notify them of emergencies or pressing legal matters. 

Many regional registries place limits on the volume of queries that any one IP address can make. The limits are high enough for most people; if you exhaust all your available searches, you can try again later. Contact our staff for solutions that will enable you to export details on a large list of domains.

What Is the WHOIS Database?

After the launch of the World Wide Web, system administrators found a need to search for detailed information on domain registrations. Few tools existed at the time to help them with their searches. Many of the domain searching tools that did exist ran from the command line on mainframes and servers.

Most people did not have ready access to WHOIS since no WHOIS searching tool was available on most users' Windows or Macintosh computers. Domain registrars had to find a way to let clients run WHOIS searches without installing software, leading to the creation of web-based WHOIS searching tools.

The earliest web-based WHOIS tools pulled results from Unix command-line tools. They displayed the raw WHOIS data in a human-readable but primitive manner. Modern web-based WHOIS tools such as Whois Checker format and organize the information. This makes it easier to read and link to other databases. Whois Checker displays all information contained in the WHOIS database for a domain or IP address.

Although the early WHOIS database served only as "white pages" for the Internet, modern WHOIS services provide much more information. The information is made available by registrars and registries using WHOIS Services, also called Registration Data Directory Services. The process by which all of these services are tied together is largely transparent to most users. The information tracked and maintained by these services, globally, is referred to as the WHOIS database.

What Information Is Found in WHOIS Searches?

The most important information found in WHOIS is contact information. It will let you contact the person or persons responsible for any resource on the Internet. Anyone who runs a WHOIS search can see the information if it is public.

Sometimes direct contact information is not stored in WHOIS. In these cases, information in WHOIS will let you contact an organization that knows how to contact the responsible persons or corrects their data. Many times the information stays private through services that register domain names on behalf of others.

The Thin Model and the Thick Model

Not all WHOIS services provide the same information. Two prevailing models of WHOIS databases exist, the thick model and the thick model. 


A thick WHOIS server maintains the registration information for a large number of domains in its own database. When a WHOIS query runs on a thick WHOIS server, the server retrieves the information from its own database. The .org top-level domain is maintained by a thick WHOIS server.


A thin WHOIS server stores for each of its domain a link to a WHOIS service maintained by the domain's registrar. The domain registrar's WHOIS server stores the contact information for the domain. The .com WHOIS servers use the thin model.


Both approaches have their advantages and tradeoffs. The thick model runs queries faster and is more suited to maintaining canonical data. The thick model can also provide an authoritative source of information on domain registrations. The top-level server can show who owns the domains if a registrar loses its data. That could be tricky under the thin model.

The global top-level domains .net and .com use the thin model. Their authorities permit domain registrars to maintain contact information for their own domains. The other top-level global domains use the thick model. Each of the regional domains has its own rules.

Is the Information Accurate?

ICANN rules state that whenever anyone registers a new domain name, the domain registrar must to place the contact information in the WHOIS database. ICANN also requires registrars to grant domain name holders have the opportunity to update the contact information linked to their domains from time to time. Registrars must provide opportunities to correct inaccurate information. Registrars are not required to verify its accuracy.

Some domain registrars allow private registrations, where a proxy party registers the domain on behalf the principal. The proxy protects the principal's contact information from public view.

The WHOIS database is not designed to provide strong security. It does not have any built-in means for fine-grained access control, for ensuring data integrity, or for protecting confidentiality. Fortunately, those using the database must obey the laws and the policies of their registrars. When dealing with complex legal matters it is a good idea to verify the information returned by WHOIS queries with other sources.

The Fraudulent Online Identity Sanctions act makes it a crime to place false information in the WHOIS database to avoid punishment for a crime. It does not make placing false information in the WHOIS database illegal for everyone; it only makes it illegal if false information is used in an attempt to elude law enforcement.

ICANN seeks to maintain a high level of data integrity in the WHOIS database. It accepts complaints from parties that discover inaccurate WHOIS data. When a party registers a valid complaint, domain registrars must correct and verify their data.

Who Uses It?

Many third parties may search the WHOIS database, including:

  • Individuals checking for unclaimed domain names.
  • Service providers who want to verify ownership.
  • Investigators looking for sources of criminal activity.
  • Trademark holders using it to figure out who might be infringing on their copyrights

Laws and policies protect the WHOIS database from being bulk queried by spammers or con artists.

How Do I Update My WHOIS Information?

To update your WHOIS information, simply contact your domain registrar and ask them to update it. Most registrars have simple web-based forms that will let you correct your contact information or add any missing details. Some can make the changes over email or over the phone.

If you are concerned about spam or other unwanted solicitations, most will also offer privacy options that will keep your contact information out of the public WHOIS database. Your contact information will still be maintained by the domain registrar in case someone has a legitimate reason to contact you.

Who Is in Charge of WHOIS?

The top authority over WHOIS is ICANN, the Internet Corporation for Assigned Names and Numbers. ICANN has designated several Regional Internet Registries (RIRs) that maintain records for geographical areas. An RIR is an organization responsible for registering and distributing Internet numbers within a particular region.

RIRs are the ultimate authority for assigning IP addresses and autonomous system numbers to networks in their respective areas, in accordance with their regional policies. The RIRs provide WHOIS services that can be queried directly to identify the domain registrar for an Internet resource. Each RIR is indexed to each other RIR so that a query to one for information under the purview of another will return a link to the authoritative registry. A query to APNIC on a domain overseen by AfriNIC will return a document pointing to AfriNIC. 

The RIRs are:

  • African Network Information Centre (AfriNIC)
  • American Registry for Internet Numbers (ARIN) 
  • Asia-Pacific Network Information Centre (APNIC) 
  • Latin America and Caribbean Network Information Centre (LACNIC) 

Several commercial WHOIS servers are also maintained. 

How Does WHOIS work?

The low-level details of the WHOIS protocol are not seen by most users. You won't need to know exactly how it works to use Whois Checker. For those who want more technical details, an early specification can be found in RFC 812.

Around 1982, WHOIS was referred to as NICNAME. Under the hood, it functions much like the NAME/FINGER protocol. 

The specification spells out a simple sequence that involves first establishing an unencrypted TCP connection on port 43. The client then sends a single command, followed by a carriage return and line feed. The server returns a result and closes the connection.

Ordinarily, the command line would simply be the name of the resource for which the client seeks details, but many servers accepted more complex command lines and provided a help system for preparing more detailed queries.

The protocol was so simple that many users did not use special software to access WHOIS, instead making network connections to WHOIS servers and typing their commands to them directly.

WHOIS has seen a few refinements over the years but still works much as the original as specified in 1982. You can find the most recent specification in RFC 3912.

History of WHOIS

In the early days of the ARPANET, the Department of Defense took charge of all domain registrations. All WHOIS queries were handled by a single server.

As the ARPANET became the Internet, the Department of Defense continued to maintain authority over domain name registrations until 1993. The National Science Foundation issued a resolution stating that Internet domain registration should be handled by the private sector. InterNIC, a coalition of commercial entities was formed to handle domain registrations.

In 1999, ICANN took charge of top-level domains .org, .com, and .net. They chose to adopt a thin WHOIS model for the domains. Existing WHOIS software did not function well with the thin WHOIS model; ICANN quickly launched one of the first web-based WHOIS lookup tools, designed to select WHOIS servers using a top-level domain table. Most modern WHOIS software is structured much the same way but with a far more complex and detailed index of WHOIS servers.

The number of top-level domains exploded from only a few to hundreds over the next several years. To do a WHOIS search on a domain requires identifying the right WHOIS server. Advanced tools for navigating the complex web of WHOIS services were developed. With Whois Checker, you can run complex and detailed WHOIS queries without thinking about the innermost workings of the WHOIS protocol. It just works.