
Quote from iqfeed:
After seeing this thread, we did some checking in our network and were able to determine that one of our server farms has a bad switch that is flooding our internal network. This would only affect users connected to the x.x.156.x server farm. We will be taking that network down tonight to correct the problem (see http://forums.dtn.com/index.cfm?page=topic&topicID=1819 for more information).