I have noticed that an unrelated domain name is now pointing to my site. The DNS is pointing the domain to my IP. I'm not sure if it is a mistake, or if someone has done it on purpose. It would seem to me this could make Google look at it as duplicate content, or a doorway site and potentially penalize my site! Is this possible? Are there other ways someone could try to get my site penalized on purpose such as posting it on a notorious link farm?