A certified ethical hacker is conducting a Whois footprinting activity on a specific domain.

A thin Whois model is a type of data model that is used by some domain registrars for storing and looking up Whois information. In a thin Whois model, the registrar only stores the basic information about the domain, such as the domain name, the registrar name, the name servers, and the registration and expiration dates. The rest of the information, such as the contact details of the domain owner, the administrative contact, and the technical contact, is stored by the registry that manages the top-level domain (TLD) of the domain. For example, the registry for .com and .net domains is Verisign, and the registry for .org domains is Public Interest Registry. When a Whois lookup is performed on a domain that uses a thin Whois model, the registrar’s Whois server only returns the basic information and refers the query to the registry’s Whois server for the complete information1.

As a hacker, if you are unable to gather complete Whois information from the registrar for a particular set of data, it might be because the domain’s registrar is using a thin Whois model and the registry’s Whois server is not responding or providing the information. This could be due to various reasons, such as network issues, server errors, rate limits, privacy policies, or legal restrictions. Therefore, the probable data model being utilized by the domain’s registrar for storing and looking up Whois information is a thin Whois model working correctly.

References:

Differences Between Thin WHOIS vs Thick WHOIS – OpenSRS Help & Support