Content distribution networks (CDN) help manage high-traffic sites by caching content on a network of servers close to the edge of the network, allowing the traffic to be distributed among many servers instead of focused on a single point on the network. CDNs are also used to defend against DDoS attacks, using their networks of servers to blunt an attack’s impact. Microsoft used a CDN service from Akamai to keep its web site online last August, when the Blaster worm programmed machines to launch a DDoS on the Windows Update site.

The nature of Akamai’s network has earned it the attention of hackers, including the Fluffi Bunny group, which claims to have stolen files during a network intrusion in April 2001. The group reportedly hoped to use Akamai’s thousands of servers in a concerted attack on the DNS system. Akamai disputed the claims and said its network was never in danger of being used in such an exploit. The assumed head of Fluffi Bunny arrested last year at the InfoSecurity Europe 2003 trade show in London.