This paper addresses two unresolved issues about web caching. The first issue is whether web requests from a fixed user community are distributed according to Zipf's law [22]. Several early studies have supported this claim [9], [5], while other recent studies have suggested otherwise [16], [2]. The ;econd issue relates to a number of recent studies on the characteristics of web proxy traces, which have shown that the hit-ratios and temporal locality of the traces exhibit certain asymptotic properties that are uniform across the different sets of the traces [43, [XO], [71, [XO], [XS]. In partlc- ular, the question is whether these properties are inherent to web accesses or whether they are simply an artifact of the traces. An answer to these unresolved issues will facili- tate both web cache resource planning and cache hierarchy design

Designing a distributed cache infrastructure to improve the Web performance for the users of a large-scale organization is a difficult task. To guide the decisions of system administrators, we propose Saperlipopette!, a tool that can be used to evaluate, a-priori, the quality of the service offered by each potential configuration of the distributed cache infrastructure. Saperlipopette! is based on trace-driven simulations. Our methodology is two-fold. First, we monitor the targeted organizations' Web related activity. Second, we replay the organization's access pattern while simulating the distributed Web support infrastructure. This paper presents the information gathering as well as the design of the tool. We show that beyond a certain cache's size, the performance stays constant whereas the consistency continues to decrease. We also evaluated a number of distributed configurations, among which peer-to-peer Relais cooperation proved to be the best one. Keywords Web caches, configur...