I understand that's annoying, and hope to improve it. The system reports digit.com free because it doesn't have an A record, but I will fix this by checking SOA records in the future. I'm not sure why 6af.com is reported free, maybe there was a temporary DNS problem when I checked it. It should be updated in a couple of days.
You could first try the ANY query (which won't return all records though) and then a whois query on failed ones to be sure. Combined with some smart caching and affiliate/click tracking (to see if a new domain gets registered).
