The two online examples discussed in this section demonstrate the response time improvements gained from using a CDN. Both examples include the same test components: five scripts, one stylesheet, and eight images. In the first example, these components are hosted on the Akamai Technologies CDN. In the second example, they are hosted on a single web server.
The example with components hosted on the CDN loaded 18% faster than the page with all components hosted from a single web server (1013 milliseconds versus 1232 milliseconds). I tested this over DSL (~900 Kbps) from my home in California. Your results will vary depending on your connection speed and geographic location. The single web server is located near Washington, DC. The closer you live to Washington, DC, the less of a difference you'll see in response times in the CDN example.
If you conduct your own response time tests to gauge the benefits of using a CDN, it's important to keep in mind that the location from which you run your test has an impact on the results. For example, based on the assumption that most web companies choose a data center close to their offices, your web client at work is probably located close to your current web servers. Thus, if you run a test from your browser at work, the response times without using a CDN are often best case. It's important to remember that most of your users are not located that close to your web servers. To measure the true impact of switching to a CDN, you need to measure the response times from multiple geographic locations. Services such as Keynote Systems (http://www.keynote.com) and Gomez (http://www.gomez.com) are helpful for conducting such tests.
At Yahoo!, this factor threw us off for awhile. Before switching Yahoo! Shopping to Akamai, our preliminary tests were run from a lab at Yahoo! headquarters, located near a Yahoo! data center. The response time improvements gained by switching to Akamai's CDNâas measured from that labâwere less than 5% (not very impressive). We knew the response time improvements would be better when we exposed the CDN change to our live users, spread around the world. When we exposed the change to end users, there was an overall 20% reduction in response times on the Yahoo! Shopping site, just from moving all the static components to a CDN.
Use a content delivery network.
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