Desire to connect various portable devices such as laptops, PDAs, smart phones etc with internet at anytime, anywhere and any how lead to the development of wireless networks. Mobile ad hoc networks (MANETs) consists of such devices, which are portable in nature such as laptops, mobile phones or personal digital assistants for initiation of communication. A large number of ongoing research and development in the area of MANET is constrained to the single networks and stand alone. Mobile ad hoc networks require the interconnection with internet because a broad range of services and applications rely on wired infrastructure networks now-a-days. Therefore, there is a necessity that ad hoc networks should have access to wired networks along with their services. This interconnection of MANET and internet enhance the plasticity of networking and improve the infrastructure networks coverage area. Many solutions have been proposed by researcher for this integration, but which solution among these are comparatively better is still vague. It is mandatory for a node of ad hoc network to discover and select the most appropriate internet gateway in order to achieve the access to internet. This study focused on the various issues and challenges of internet integration along with the different proposed solutions on gateway discovery and issues associated with them.