The first category is well known, at least to people who work in and around the domain industry: domains in the Redemption or Pending Delete periods. Each day tens of thousands of .com domain names hit their renewal date. There are currently 2.1 million .com domain names in either Redemption or Pending Delete status.
The second category is much less well known, a category DomainTools refers to as ‘dark domains’. Domain names that exist, but are not pointed to nameservers, are not listed in the zone file and therefore not counted by most sites that track domain registration data. An example of such a domain is Spectrum.com; it exists but has no nameservers, and does not resolve to a website. Another example is theexpertcare.com; the Whois record indicates a fraud alert on the domain name and a ‘suspended’ status. This domain is also not in the zone file and yet is certainly not available for anyone to register.
Only Verisign knows for sure how big the list of dark domains is, but we have conducted ongoing proprietary research that reveals over 400,000 known dark .com domain names, as found in blank-nameserver.com. This count is included in the recently updated domain statistics data on our DailyChanges.com website. Our calculation of .com domains includes those listed in the zone file plus the dark domains. With that information in mind, we calculated the current total of .com domains managed by Verisign to be over 100.2 million.
100 million actively registered domains is an enormous achievement for the dominant TLD worldwide, and congratulations are in order for Verisign and the registrars which support .com! For the full article and research information head on over to http://blog.domaintools.com/2012/01/our-estimate-verisign-manages-over-100-million-com-domains/