That can be in your router choice so you as the admin would know which DNS you are using.
I got a "This domain is blocked " msg from the Huffingtonpost.com site while attempting a search that was trying to access "search.huffingtonpost.com. The screen also said this happened "based on category choices" re "News/Media/Blogs/Politics" and seemed to be coming from "blocked-website.com." Also said I should contact my network administrator. Well, that's me and I am the only user on this computer (an older MacBook). I have looked at Mac Preferences as well as settings for Safari and Firefox and cannot figure how or what was blocked to be able to unblock - can someone guide me here?