During lunar landing, exhaust from the retro-rocket strikes the lunar surface producing a shock close to the surface. The post-shock pressures near the lunar surface cause entrainment of dust in the plume, which may prove to be hazardous to the rocket. In the present study, the rarefied flow away from the lander nozzle is predicted using the Direct Simulation Monte Carlo (DSMC) method to investigate rocket-plume impingement on undulated surfaces to study the effect of surface roughness on plume movement. Comparative analysis with plume impingement on the flat surface shows that static pressure distribution along the lunar surface is uneven and peaks at crests on the undulations.