Abstract. Web caching plays an important role in many network services. Utilization of the cache in each level (server, proxy, and client) of network forms a web caching hierarchy. A major problem of the hierarchical caching is the poor performance due to the interference between upper-level and lower-level caches. This paper investigates the replacement algorithms applied in the network caching hierarchy through trace-driven simulation experiments to identify the performance bottleneck. Our investigation focuses on three fundamental replacement algorithms: LRU, LFU and SIZE, because many other replacement algorithms are mainly the variations and/or combinations of the three fundamental algorithms. Through extensive experiments, we have acquired useful performance features of these algorithms and their combinations at different levels. Thus, our work may serve as a reference for the design and deployment of efficient replacement algorithms in the caching hierarchy for web engineering.