It is impossible, indeed. There are just too many ISPs/DNS servers/whatever to take them all down.Afaik, some really strong DDoS-attack some months ago caused a lot of trouble because large european areas were cut off the internet, but after 30 minutes most system administrators managed to protect their systems, and everything went back to normal.An EMP bomb on the 10 biggest cities in every country wouldn't destroy it either, because there are still satelites out there, sending and receiving invisible data packets...