While the incident appears to have been an accident, it underscores the weakness of the Border Gateway Protocol (BGP), a critical, but obscure, protocol used to bind the Internet together.

BGP data is used by routers to tell them how to route traffic over the Internet. Typically smaller service providers "announce" BGP routes for the networks they control, and that information is ultimately centralized and then shared between larger providers. That's where the problems started on Thursday. For some reason, IDC China Telecommunication announced routes for tens of thousands of networks -- about 10 percent of the Internet. Typically this small ISP announces about 30 routes.

That bad information was then accepted by the larger China Telecommunications, which shared the data with other major ISPs. Within minutes the bad data had spread around the globe.

ISPs may have accepted the hijacked route information, but that doesn't necessarily mean that a lot of Web surfers got redirected. It's common for routers to learn several BGP routes, and then route traffic to what they consider the best route. Often they choose the shortest route available. So most routers in the U.S. would have routed traffic to Apple's servers, for example, instead of IDC China Telecommunication.

"I don't believe there was really widespread impact, but some people must have noticed it," said Andree Toonk, founder and lead developer of BGPmon.net, a BGP monitoring service that has been . "Many people probably didn't prefer the path because they had a better path."