The Leap Second which occurred yesterday, effectively brought down half the internet. Google explains it best, as well as how they prepared for it. However, many of the most popular sites and applications on the internet were not prepared for the leap second adjustment, and many of them saw widespread outages as soon as the adjustment took place. http://www.buzzfeed.com/summeranne/y2k-20-how-a-second-brought-down-half-the-intern