Despite hierarchical Distributed Hash Table (DHT) systems have addressed flat overlay system problems, most of existing solutions add a significant overhead to large scale systems. This not only increases the bandwidth consumption but also affect the routing efficiency. This paper deals with a resource discovery while minimizing maintenance overhead in hierarchical DHT systems. The considered resources are metadata describing data sources. In the solution, only one gateway in one overlay is attached to the superior level overlay. It aims to reduce both lookup and maintenance costs while minimizing the overhead added to the system. The authors present a cost analysis for a resource discovery process and discuss capabilities of the proposed protocol to reduce the overhead of maintaining the overlay network. The analysis result proved that our design decrease significantly the maintenance costs in such systems especially when nodes frequently join/leave the system.