<b>Simulations on Computer Network An Improved Study in the Simulator Methodologies and Their Applications</b> Generally a network simulator is used to analyse the performance and behaviour of a network. The Simulation software plays a vital role in real world implementation. The hardware setup of network topologies are very costly and strenuous to modify often. The simulators act as the protocols for a system. The simulators in network such as Ns 2, Ns 3, OMNeT , NetSim, J SIM, REAL, OPNET, OMNEST, QualNetTraNS, NTCUns etc. It is quite a tedious process to select network simulator that is based up on the requirement for a users specified job. This paper gives a comparison and a general analysis of various network simulators. Network, Simulator, NS2, NS3, OPNET, OMNeT , QualNet, NetSim and J Sim 144-146 Issue-4 Volume-5 J. Sumitha | S. Swathi | Ellakkiya. M