On the Tails of Web File Size Distributions

Power laws have been observed in various contexts in the Internet. There has been considerable interest in identifying the mechanisms behind these power laws. Most of these have focused on the tail behavior of the distributions. We argue that the the tails and their asymptotic behavior is very hard to substantiate in realistic engineering systems. In this paper we describe some of the proposed mechanisms for producing power law tails. We show that these mechanisms are not particularly robust. Furthermore, we argue that the data ususally available for classifying a distribution is insufficient to classify the tail. Fortunately, the tail has little impact on Internet performance. Thus it is sufficient to focus on mechanisms leading to power law like “waists” of the distributions.