A tale of three CDNs: An active measurement study of Hulu and its CDNs

We study the Hulu online video service via active measurements. It is known that Hulu utilizes multiple CDNs to serve users´ video requests. The focus of this study is on how Hulu selects CDNs and how each CDN allocates resources (i.e., servers) to serve user requests. Based on our analysis of measurement data, we find that Hulu frequently changes preferred CDNs for users. However, once a CDN is selected, Hulu clients try to stay with the same CDN during the entire length of the movie even when performance of that CDN degrades. While the preferred CDN selection is not fixed, we observe that Hulu attempts to divide video requests among CDNs to attain a fixed target ratio. In terms of CDNs, we find that different CDNs employ different amounts of resources (servers) to serve Hulu content.