This has come up a few times before, I think most recently at https://news.ycombinator.com/item?id=6340862 https://news.ycombinator.com/item?id=6340862 . It see

This has come up a few times before, I think most recently at https://news.ycombinator.com/item?id=6340862 https://news.ycombinator.com/item?id=6340862 . It seems whois is a bit ambiguous and picks up subdomains for some reason.