There seems to be an issue with Level 3 at the moment which is causing all sorts of sites to be unreachable for some people but not others. Rackspace (mail, hosting, cloud, etc), Facebook, Hotmail, Github, Digital Ocean, etc.
For those experiencing connectivity issues, try a different ISP/network. For example, I can't connect to any of the above networks via my regular Time Warner cable connection or via my T-Mobile hotspot. But I can connect via my Verizon hotspot.