About the WHOIS / RDAP check tool

Using the WHOIS tool, you can search for information on domain names, IP addresses, ASN’s and their associated CIDR-ranges. The returned information may include info on owner/manager, contact information, and any relevant technical details.

The tool allows you to make
  • Classic WHOIS lookups
  • RDAP lookups, for more accurate and up-to-date information
The tool allows you to search for:
  • Domain names
  • IP addresses
  • ASN’s - network operators of the internet
  • CIDR’s - ip blocks/announced prefixes maintained by the network operators (ASN’s)


For a quick introduction, try out these WHOIS-lookups:
WHOIS of google.com WHOIS of facebook.com WHOIS of bbc.co.uk WHOIS of WHOIS of ASN15169


What is WHOIS and what information does it provide?

WHOIS is a database lookup service, based on a simple query/response protocol. It is used to provide information about domain names, IP addresses, ASNs and CIDRs, making it a valuable resource for anyone looking for ownership and technical details of a particular online entity.

What is RDAP and why is it used in this tool?

RDAP, or the Registration Data Access Protocol, is a standard protocol for accessing registration information, using RESTful API calls. RDAP provides a more secure, flexible, scalable and standardized way of accessing WHOIS information compared to the traditional WHOIS protocol.

What is an ASN and a CIDR in relation to WHOIS?

The Internet is a vast network of smaller interconnected networks. These smaller networks, often called autonomous systems (AS), are responsible for managing the flow of data between different parts of the Internet.

Each AS is assigned a unique identifier known as an Autonomous System Number (ASN). The ASN is used to identify the operator of the network and to control the routing of Internet traffic to and from the network.

Using WHOIS and/or RDAP you may lookup details on each of these ASN’s.

Furthermore - each AS/ASN manages one or more blocks of ip addresses on the internet. These blocks are called network prefixes, and are described using the CIDR notation. These CIDRs, and all related technical information, is also searchable using WHOIS and RDAP.

Is the information in a WHOIS search result always up-to-date?

WHOIS information is maintained by third-party organizations, and is therefore subject to updates and inaccuracies. While the accuracy of the information can vary, the online WHOIS tool will provide the most recent information available in the WHOIS database at the time of the search. However, it is important to keep in mind that WHOIS information may not always reflect real-time changes, such as the transfer of a domain name to a new registrar or the assignment of a new IP address.

What if the information I'm looking for is not available in the WHOIS database?

In some cases, the WHOIS information may not be available in the WHOIS database. This can occur for several reasons, such as if the registrar or registry has not yet updated the information, if the domain name is being transferred to a new registrar, if the domain name is new and has not yet been fully registered or if the information has been redacted due to privacy reasons.

If the information you're looking for is not available in the WHOIS database, you can contact the relevant registrar or registry for more information.

How does WHOIS and RDAP work from a technical perspective?

There are minor differences, but in general, you can query any WHOIS server by opening up a TCP/IP connecting to it at port 43, and then just simply typing in the domain or IP-range you would like to get info on.

Webpages and tools, such as iamroot.tech, do nothing special but this – when you hit the submit button, we traverse the WHOIS structure, until we get the correct info for you.

RDAP works a bit differently, as it is based on RESTful API’s using HTTP communication. The query is basically contained in the URL, and the response is a very well structured JSON result. This makes RDAP less readable for humans, but as the information is way better structured and standardized, it is perfect for code and software to parse, use and display in a readable manner.

WHOIS and RDAP specifications (RFC’s)

The original specification for WHOIS was documented in the early days of the Internet in RFC 812 (1982), but this has since been updated and superseded by (among others) RFC 3912.

RDAP (Registration Data Access Protocol) is a newer protocol that is intended to replace WHOIS as the standard for accessing registration data. The main difference between RDAP and WHOIS is that RDAP provides a more structured and standardized format for the data returned, making it easier to automate and process the data. The current standard for RDAP is defined in RFC 7482.

These RFCs provide the technical specifications and guidelines for using WHOIS and RDAP, and are essential references for anyone who is working with these protocols.


This tool has a fully-featured API available. You may read more about the API here. It is also an option to simply try out the tool - the corresponding API URL for each lookup is made available as a part of the result.


These tools are still in active development. If you have any kind of feedback, please let me know. Send me an e-mail on iamrootdottech(a)gmail.com.