Ever thought about how ACS gets an end users IP or how when showing an interfaces authentication sessions it had the IP of the host attached? This all stems from IP Device Tracking. I only recently came across it when troubleshooting an issue we had with windows machines not getting a DHCP address due collision detection involving the 0.0.0.0 address. Although there are lots of posts about people having a similar issue and the workarounds, I couldn’t find much information on the exact reason why this happened. This post is designed to give more reasoning on why this happens.
