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GCN Home > March 4, 2002 issue

Load Balancing

By William Jackson, GCN Staff

CDC site focuses on distributed content

The 7-year-old www.CDC.gov, Web site of the Centers for Disease Control and Prevention, has been on what CIO Jim Seligman calls “a continuou
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Turning on the Akamai service to balance CDC’s Web site “was an easy implementation, which is quite unusual in the IT realm.”
—JIM SELIGMAN
s growth curve.”

The site hosts 120,000 pages and dozens of databases used by the public and health care professionals. Through September 2001 it was averaging 4 million unique visitors each month.

“That’s among the top government Web sites,” Seligman said. “Since the anthrax business, usage has jumped.” After counting more than 9.1 million visitors in October, 5.2 million in November and 7 million in December, CDC turned to a managed-content delivery service from Akamai Technologies Inc. of Cambridge, Mass.

The site quickly became one of the fastest government sites on the Keynote Government 40 performance index. CDC.gov took the No. 2 spot in December with an average response time of 0.44 seconds. It remained No. 2 for five weeks.

“That was a nice by-product,” Seligman said of the ranking from Keynote Systems Inc. of San Mateo, Calif., but he was more interested in sustainability and reliability. By caching data on Akamai servers around the world, Seligman said, CDC could keep its site available in spite of network interruptions, traffic spikes or cyberattacks.

No stale news

The EdgeSuite service redirects visitor requests to Akamai’s Domain Name System server, which sends them to a caching server at the Internet’s edge. CDC’s host servers are polled only for dynamic or updated data. That reduces their workload, improving availability and relieving the need to upgrade and manage a larger infrastructure.

The edge servers also help shield CDC data centers from intrusion and absorb traffic from service denial attacks. The Akamai service uses about 13,000 servers on 1,000 networks in 63 countries. It also can provide backup by delivering stored or default pages when a host server is down.

More news on related topics: E-Government