I have a (test) domain name I use for development. Perhaps I should be using a sub-domain name. But I don't.
I know of no published link to this domain anywhere. Sometimes--while developing a new website--I forget to put a meta NOFOLLOW element in the headers of the new pages I'm generating.
Interestingly, keyword searches on the content of those new and not-yet-published websites often end up indexed on Google. How did Google ever know about that domain in the first place, when I never (ever) published a link to it?
I suppose it only has to be spidered once and then it's a known entity for ever. But I am still curious to know how they ever found out about my test domain in the first place. Is NOFOLLOW the only way to have a test domain? Or are sub-domains a better way to go?