Robustness of the 19-inch racks are tested when strong artificial vibrations are added them. We have confirmed that four kinds of rack we chose have rigidity up to 300gal to ground level accelerated velocity by itself. Also it shows the same result that the network devices installed in the rack-mounted way or tightened with surface fastener. It means that 19-inch racks and the network devices work properly during adding the vibration. We have confirmed four kinds of different way of installation of the network devices in the rack; it turns out to be the figure of each accelerating dynamic magnification has little practical difference.