World-Wide Web caches are designed to alleviate some of the problems imposed by ever-increasing Internet traffic growth. Caching is noticeably different from mirroring or replicating; It is mostly transparent to end users, and because caches are client-driven, they automatically adjust to accommodate popular objects based on user access patterns.

The National Science Foundation has provided funding to develop a prototype hierarchy of World-Wide Web caches, which have been in operation since December 1995. This paper describes our initial experiences and observations while operating the caches. In particular we focus on the administrative requirements for configuring and tuning a cache for its best performance in the global hierarchy.