What is webfilterdnsd process?
Although it doesn't answer your question directly, the excellent

http://triviaware.com/macprocess/all

is a web resource that describes many Mac processes. 

It describes webfilterDNSd as:

"Process is part of clean OS X install however there is no description available from credible sources at this moment. Use supplied link for related google search."

There's a comment section by which others that know might be able to answer your question.