5.2.c [iv] Device tracking
The IPv6 Device Tracking feature provides IPv6 host liveness tracking so that a neighbor table can be immediately updated when an IPv6 host disappears. The feature tracks the liveness of the neighbors connected through the Layer 2 device on a regular basis in order to revoke network access privileges as they become inactive.
Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 5378-5380). . Kindle Edition.