I've got a third party commercial application that sends out a UDP broadcast and expects a response from machines on the same network. This works fine when only one NIC(we'll call it "primary") is enabled but if I enable the "secondary" adapters it fails. It seems like the problem is in how the app is determining which NIC to use. Is there a tool that would let me interrogate or watch what the app is doing to determine which NIC to send the traffic out on? I've taken Wireshark traces and that has shown me the traffic but I need something that will give me more information at an earlier phase in the process. I've also looked at some of the Sysinternal tools and wasn't sure if one of those might do the trick. Seems like I need to watch the app start and somehow watch it go through the process of selecting an interface to use. Is this possible?OS is either WinXP and/or Win2008 32 or 64 bit. 1 person got this answerI do too