In a significant attack on the Internet, hackers tried and failed to bring down the Internet yesterday.

By sending large volumes of data in a something called a denial-of-service attack, the hackers attempted to stop the servers that are relied upon to direct internet traffic.

The three root servers are all operated by different organisations - the US Defense Department, ICANN, and UltraDNS, which directs traffic for ".org" websites.

The attack meant that the servers were bombarded by data, in an attempt to bring them down by pushing them to their limits.

It was most probably done with computers that had been previously hacked in order to carry out the attack.

ICANN's executive officer, Paul Levins, treated the resulting non-event as a success. "Last night we were seeing attacks which lasted for a couple of hours", he told the BBC.

"There were probably hundreds of root server operators co-operating around the globe to make sure that the average user wouldn't notice."

"The most interesting element of this concerted attack is that the system demonstrated the benefits of being dispersed and interoperable. There was no one point of failure", said Mr Levins.

The reasons behind the attack aren't known, but it was probably just down to mischief-making, rather than any more sinister cause, although it could have also been motivated by a desire for money through blackmail if the servers were brought down.