Akamai

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said a disruption of service at major Internet sites Tuesday morning was caused by "a sophisticated, large-scale attack that Akamai identified as being targeted at specific Web sites that are Akamai customers."

Akamai, a Cambridge, Mass., Web-hosting service, said its staff quickly detected the problem and made adjustments along with partners to shut down the source of the attack. The company made the comments in a Wednesday morning summary of Tuesday's events.

On Tuesday, the IDG News Service reported that an attack on the Internet's domain name system -- a directory used to locate Web addresses -- caused disruptions at

Yahoo!

(YHOO)

and other sites. Web tracker Keynote Systems said the attack disrupted service at sites run by

Google

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and

Microsoft

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as well,

Reuters

reported.

Wednesday morning, Akamai offered additional details on the event.

"The attack impacted Akamai's Internet naming functionality (Domain Name Service, or DNS) and resulted in delays in DNS name resolutions and, in some cases, timed-out DNS requests," the company said. "Some Internet end users trying to reach affected sites experienced slow responses from Akamai's DNS servers, resulting in page time-outs. The attack did not cause an outage in Akamai services, as Akamai continued to serve both DNS requests and website content for customers throughout the period of the attack. The Akamai Domain Name Service returned to normal by 10:45 AM ET on Tuesday, June 15."

The attack took some blame for an untimely slowdown in the Yahoo! Mail service, which the company relaunched yesterday with some fanfare.

"There was a widespread DNS issue that may have affected numerous Internet sites and we are currently investigating its impact on our services," Yahoo! said Tuesday. "Also, as we upgrade tens of millions of Yahoo! Mail accounts for consumers worldwide, some users may experience temporary fluctuation in service as we update our systems. We expect Yahoo! Mail accounts to resume to normal after upgrades are completed."