Tell HN: dnsexit.com is down since hours
Check your domains, dnsexit.com has been down for probably half a day now - not only their website, but also their redundant DNS servers.
Actually there are a couple of free alternatives. Previously I've been at zoneedit.com, which worked pretty nice. I can't even remember why I switched.
Google also offers public DNS[1] as well as a wide range of free service providers when you search for them[2].