Originally posted by flipped cracker
the worst one i can think of to date (atleast, worst to me) is when the group of hackers tried to bring down all the root dns server (basically the servers that run the internet) and came pretty close to bringing them all down.
worse yet, replacing the valid root DNS information with other data. the data would propagate to all the other DNS servers everywhere else, causing a mess that would take days to recover from AFTER the corrupt data was repaired.