I just read an interesting article Who is blocking Whois. It turns out that ICANN stipulates all registrars must provide WHOIS database access via port 43. Garth Bruen, knujon.com, did a full analysis of all registrars testing their WHOIS database uptime — that’s assuming he was able to determine their WHOIS database address. ICANN assumes in good faith registrars will follow convention and locate their lookup servers at whois.registrar.TLD. Some registrars don’t even advertise the address (if they are providing access at all). I hope you’re not supporting any of the guilty registrars on the list….