Fast and efficient large content distribution is a challenge in the Internet due to its high traffic volume. In this paper, we propose ChunkCast, an anycast service that optimizes large content distribution. ChunkCast is a distributed locality-aware directory that supports a chunk anycast query for large content efficiently. Our preliminary evaluation shows that ChunkCast improves the median downloading time by at least 32% compared to previous approaches and emulates multicast trees without any explicit coordination of peers. (This is joint work with Peter Wu, Hakim Weatherspoon, and John Kubiatowicz. This paper appeared in IPTPS 06.)