I see some are having DNS problems and others recommending Googles DNS. I would like to recommend, to those on a Windows system, to give DNS benchmark a try by Steve Gibson
http://www.grc.com/dns/benchmark.htm. Using this tool you can find the best DNS server for your connection.
No, it's another problem.
Those DNS-servers don't respect TTL field and still point to an old IP when it should be new already.