This paper proposes a novel file searching protocol to structure a DHT ring consisting of only super-peers, not all nodes, for locating rare files with low file search cost and considerably improving speed and accuracy of query matches than Gnutella-like searching ones. In an N-node network, a node of the previous DHTs requires routing information about (logN) other nodes for searching the key of a desired file and O(logN<SUP>2</SUP>) messages to update routing information in the network on node join and leave operations. But in our protocol, if the number of super-peers is n in the N-node network, the protocol needs only O(logn) routing information and O(logn<SUP>2</SUP>) maintenance messages respectively. This feature allows our protocol to be much more scalable and resilient to the churn rate than the existing DHT ones.