Dissecting State-of-the-Art Video Distribution Networks:

We are conducting a detailed study of the YouTube CDN with a view to understanding the policies used to determine which data centers users download video from. Our analysis is conducted using unique week-long datasets simultaneously collected from the edge of five networks - two university campuses and three ISP networks - located in three different countries. Our analysis employs state-of-the-art delay-based geolocation techniques to find the geographical location of YouTube servers. Our results indicate that the RTT between users and data centers plays a prominent role in the video server selection process. More interestingly however, our results reveal a variety of factors besides RTT can influence server selection including load-balancing, diurnal effects, DNS misconfiguration, limited availability of rarely accessed video, and the need to alleviate hot-spots that may arise due to popular video content.