Vivisecting YouTube: An Active Measurement Study

We build a distributed active measurement infrastructure to uncover the internals of the YouTube video delivery system. We deduce the key design features behind the YouTube video delivery system by collecting and analyzing a large amount of video playback logs, DNS mappings and latency data and by performing additional measurements to verify the findings. We find that the design of the YouTube video delivery system consists of three major components: a "flat" video id space, multiple DNS namespaces reflecting a multi- layered logical organization of video servers, and a 3-tier physical cache hierarchy. Further, YouTube employs a set of sophisticated mechanisms to handle video delivery dynamics such as cache misses and load sharing among its globally distributed cache locations and datacenters