Only if you disclose your pseudonym, if any, or even use a social networking site. Other than that the employer would have to obtain your IP address to trace back postings to you. That would be unlikely.
If you do like Facebook etc. maintain 2 accounts one of which is squeaky clean and is used in effect as a virtual resume.
Think before post. Case in point the rioters in Vancouver whose Facebook antics came back to bite them.
Thank you, but my facebook account does not have my real name on it. I also use a photograph of my best friend’s kitten or something generic — never a real photo of me.