This paper presents the design and evaluation of FastAd, a fast and highly adaptive peer-to-peer(P2P) lookup system for medium-scale network where the number of nodes is not more than tens of thousands. Using routing tables larger than those of previous schemes, a lookup can be performed at just two hops, while maintenance cost of tables can be minimized by adopting lazy consistency with piggybacking. In addition, assigning dynamic node idetifier(nodeId) instead of a fixed nodeId by hashing the node?s IP address, FastAd network can be organized more adaptively and adjusted dynamically with system state such as load distribution, node dynamics, and so on. As a result, each node has different responsibility to exploit its heterogeneity.