Thick and Thin Registries

The .com and .net are called “Thin” registries.  This is because the registry does not keep the entire whois record.  They just keep the registrar and the name servers.  The registrars are responsible for keeping the entire whois record.  This was done in the late 1990’s because Network Solutions had a monopoly and when competition was introduced the concern was that they would use their market position to take business from the new registrars.  Even though this is not relevant anymore the system has never been changed.

Other registries are “Thick” registries and they maintain the entire whois record.