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Ad Hoc network is a big collection of wireless mobile hosts forming a temporary network without the aid of any centralized administration, in which individual nodes cooperate by forwarding packets to each other to allow nodes to communicate beyond direct wireless transmission range. Routing is a process of exchanging information from one station to other stations of the network. Routing protocols of mobile ad-hoc network tend to need different approaches from existing Internet protocols because of dynamic topology, mobile host, distributed environment, less bandwidth, less battery power. Ad Hoc routing protocols can be divided into two categories: table-driven (proactive schemes) and on-demand routing (reactive scheme) based on when and how the routes are discovered. In Table-driven routing protocols each node maintains one or more tables containing routing information about nodes in the network whereas in on-demand routing the routes are created as and when required. Some of the table driven routing protocols are Destination Sequenced Distance Vector Routing protocols (DSDV), Clusterhead Gateway Switching Routing Protocol (CGSR), Hierarchical State Routing (HSR), and Wireless Routing Protocol (WRP) etc. The on-demand routing protocols are Ad Hoc On-Demand Distance Vector Routing (AODV), Dynamic Source Routing (DSR), and Temporally Ordered Routing Algorithm (TORA). There are many others routing protocols available. Zone Routing Protocol (ZRP) is the hybrid routing protocol.