The first version of ns, known as ns-1, was developed at Lawrence Berkeley National Laboratory (LBNL) in the 1995-97 timeframe by Steve McCanne, Sally Floyd, Kevin Fall, and other contributors.

From 1997 to 2000, ns development was supported by DARPA through the VINT project at LBL, Xerox PARC, UC Berkeley, and USC/ISI.

It provides substantial support to simulate several protocols like TCP, FTP, UDP, https, and DSR.

Discrete event scheduler Ns-2 incorporates substantial contributions from third parties, including wireless code from the UCB Daedelus and CMU Monarch projects and Sun Microsystems.

In 2005, a team led by Tom Henderson, George Riley, Sally Floyd, and Sumit Roy, applied for and received funding from the U.S. National Science Foundation (NSF) to build a replacement for ns-2, called ns-3.

ns-3 is written in C++ and compiled into a set of shared libraries that are linked by executable programs that describe the desired simulation topology and configuration.