Hello!

I have this little problem. A few years ago, I had couple of sites, then I closed them. But back then the search engines added those sites of mine into their databases. It's Google and Chinese Baidu. And now their bots query my DNS server for non-existent sites. The complication is this... I've got a working website today. Let's call it site.com And those non-existent sites are like that: forum.site.com (my site's subdomains).

The traffic is not significant. But why to have it on a daily basis? As far as I see it, there are two ways to possibly deal with it:
a) An administrative way, ie., to contact somehow the search engines and ask them nicely to remove those sites off their db's;
b.) A technical way, ie., to deal with it myself with some BIND9 configuration.
But I just don't know how to approach the issue, frankly.