This value, from 1 to 255, sets how much a VRRP virtual router's priority is reduced when a tracked interface goes down, and increased again when it comes back up, the mechanism that drives automatic failover to a backup router when a critical link fails. An administrator sizes this reduction so that losing the tracked interface drops this router's priority below a backup router's priority by enough margin to trigger failover reliably. With the default value of 10, a tracked interface failure reduces this virtual router's priority by 10 points.