Obviously when looking at a subdomain (sub.domain.net) it is easy to figure out the top level domain (domain.net). My question is . . . without being told about or linking to a subdomain how difficult is it to find a subdomain under a top level domain? For example if I wanted to make "family.domain.net" and put birthdays, phone numbers and such on a subdomain can some one that was not told about it, find out about it? How? Would there be a better way to execute my example?
Thanks for the help,