Mobile ad hoc networks (MANETs) are networks which routing is based on multi-hop routing from a source to a destination node or nodes. These networks have quite a many constrains because of uncertainty of radio interface and its limitations e.g. in available bandwidth. Also some terminals have limitations concerning battery energy in use.This paper deals with the challenges of ad hoc routing protocols and how to overcome routing overhead. We summarized the protocols which reduce the routing overheads and optimize the performance.