Before people panic thinking everyone's going to be cut off.....It's only a blackout for those machines that have been infected with the Trojan DNSChanger and whose owners have done nothing about it.
Until 9 July the FBI has been allowing traffic to/from those machines using special servers.
You can check it here: https://forms.fbi.gov/check-to-see-if-your-computer-is-using-rogue-DNS
As far as what one can do about preventing it I'll leave that to someone else from the VSE department.
It's nice to see at least one Government acting with a firm hand for a change.