When building or troubleshooting a network connection, it is often very beneficial to be able to watch the path that your packets take as they make their way from source to destination. Or perhaps they never make it to the destination and you want to figure out how far they do travel before stopping so that you can focus your work efforts in that area.

One command that has been used by network admins for years is trace route (tracert), but the output contains some information that is often unnecessary, and the output is missing one large key ingredient. Namely, trace route shows the first hop as the first router that you traverse and does not show you what physical NIC the packets are flowing out of. Granted, many times you only have one NIC so this is obvious information, but what if you are working with a multi-homed server and you are simply checking to make sure packets for a particular destination are flowing out of the correct NIC...