SAN FRANCISCO, Oct 23: A massive cyberattack on the computers that run the Internet was thwarted on Monday without damage, according to news reports late on Tuesday.

The so-called “distributed denial of service” attack was directed at the 13 root servers that manage the Internet’s addressing system. It lasted about an hour on Monday evening and stopped after officials took unnamed defensive actions. Internet surfers around the world felt little or no effect because of these safeguards and redundancies built into the system.

According to reports, nine of the 13 root servers were affected by the attack, which was called the worst ever perpetrated on the Internet. The FBI’s National Infrastructure Protection Center was “aware of the denial of service attack and is addressing this matter,” spokesman Steven Berry said.

The White House’s Office of Homeland Security was also said to be investigating.

Denial of service attacks can overwhelm servers by sending millions of bogus requests for information.

The attacks are often carried out through software that scours the Internet looking for vulnerabilities in personal computers which then bombard servers with requests for false information.—dpa