In peer-to-peer networks, indices are used to map data to nodes that host the data. The performance of data access can be improved by actively pushing indices to interested nodes. This paper proposes the Dynamic-tree based Update Propagation (DUP) scheme, which builds the update propagation tree to facilitate the propagation of indices. Because the update propagation tree only involves nodes that are essential for update propagation, the overhead of DUP is very small and the query latency is significantly reduced.