A single red spike in an illuminated graph suggested a major Internet traffic carrier had dropped a batch of communications, but otherwise there were no hints of data disasters.

"This is all normal," he declared. "In fact, it looks unusually good right now."

Such was not the case the morning of June 15, when the Internet's heartbeat skipped a few mega-beats and a Priority 1 alert popped up on Akamai's wall display, sending the few humans present scurrying to telephone federal authorities and alert Akamai's customers to the fact that something was amiss.

Unidentified attackers (who still have not been caught) had used vulnerabilities in the Internet's address system to interrupt traffic to Yahoo, Google, Microsoft and other large customers of Akamai's traffic management services. Leighton declined to specify what was unusual about the method — "We don't want copycats" — except to say it was aimed at the system for looking up Internet domain names.

"That was a very sophisticated attack; the nature of it was novel," Leighton recalled.

Akamai worked with federal authorities to shut down the zombie "botnets," or virus-infected computers, that had been unwittingly used to launch the attack, then designed ways to thwart repeats.

Akamai, which Leighton co-founded in 1998 with Daniel Lewin, then a graduate student at MIT, takes its name from the Hawaiian word for "smart" or "clever." The company does not have any roots in Hawai'i; according to a company spokeswoman, the name resulted from use of a search engine to find words that meant "smart" or "clever."

Today, Akamai handles about 15 percent of all Internet traffic, and helps serve the Web sites of more than 1,000 government and commercial customers, including most major news and search sites, FedEx, Apple Computer, the FBI, Defense Department and the Homeland Security Department.

Akamai also handled Web video streaming this summer for the Olympics, Major League Baseball and both presidential nominating conventions.

Akamai, with nearly 600 employees and about $200 million in annual revenue, has built a private data network of 14,000 computer servers stationed in 70 countries that sits on top of the public Internet and routes data by special formulas that seek to find the least crowded pathways. It's kind of like having a talking computer on your car dashboard tell you not to go down Main Street into the city this afternoon because an accident has caused a backup.

The company tries to speed up requests for individual Web page elements by storing copies of popular Web content in multiple locations so they can be sent shorter distances.

The firm offers other services, too, including protecting particular Internet addresses so hackers cannot use various ruses to siphon away Web traffic.

Many experts found the June 15 attack, followed a month later by other Internet infrastructure attacks, particularly worrisome because it suggested that hackers were learning how to sneak around the Internet's few defenders.

The latest Internet Security Threat Report issued by Symantec Corp. found a sharp increase — about 400 percent — in the number of hacker attacks on electronic commerce sites during the first half of this year.

"It's scary as hell," Leighton said. "The challenge for us is to stay ahead of the attackers."