SAN JOSE, Calif. -- A purported Internet attack that affected some of the world's most popular Web sites was "large scale" and "sophisticated" yet had only minimal impact, according to the targeted company.
Akamai Technologies Inc., which aims to make Internet browsing more reliable, said Wednesday that no more than a dozen of its 1,100 customers suffered a significant impact. Akamai defined "significant" as traffic being slowed for more than 20 percent of a site's users.
The company did not name the sites, though third-party monitoring services and user reports have identified them as big Internet destinations, including sites belonging to Yahoo! Inc., Google Inc., Microsoft Corp., Symantec Corp., FedEx Corp., Apple Computer Inc., AltaVista and Lycos.
Akamai spokesman Jeff Young said Tuesday the incident was a "large scale, international attack on Internet infrastructure." But it appears only to have affected the company's systems. No other companies confirmed the claim that the Internet's infrastructure was targeted.
Tom Leighton, Akamai's chief scientist, said Wednesday it was unclear whether the attack targeted Akamai or just specific customers. The result, however, was that it affected many of Akamai's systems.
"We've put several new defenses in place, and we're continuing to do additional things with our infrastructure to make such attacks less effective," Leighton said.
Akamai said the distributed denial of service attack, which floods servers with requests for information, affected its ability to translate familiar text addresses into the numbers used by computers and routers to move information on networks. Leighton would not say where the traffic originated.
From about 8:30 a.m. to 10:45 a.m. EDT Tuesday, many users found the sites sluggish or entirely inaccessible.
Akamai said it was cooperating with the FBI and other government agencies it refused to identify. The Department of Homeland Security's cyberspace division did not return a call seeking comment Wednesday. A day earlier, its chief deferred questions to Akamai.
Donna Spiser, an FBI spokeswoman in Washington, said the agency does not confirm or deny any investigations.
Leighton provided few additional details, except that the attack was coordinated, large and sophisticated. The volume of traffic was unprecedented even for a company that "sees a lot of attacks," he said.
"It had components that we had not seen before," he said, declining to comment further.
Akamai, which distributes the content of the sites on more than 15,000 servers worldwide to speed delivery and improve reliability, said third-party monitoring services overstated the impact of Tuesday's problems. Keynote Systems Inc., a monitoring service whose statements were widely reported Tuesday, said the availability of the top 40 sites it monitors dropped from 100 percent to just over 80 percent during the outage.
Roopak Patel, senior Internet analyst at Keynote, said Wednesday his company stood by its statistics.