What if the Active router uplink fails but the router itself is fine? Traffic reaches it but goes nowhere. HSRP tracking solves this.
You configure the Active to monitor an interface or route. If it goes down, HSRP decrements the priority. If this drops below the Standby priority, failover happens.
standby 1 track 1 decrement 20 track 1 interface GigabitEthernet0/1 line-protocol
With priority and decrement , the priority drops to on uplink failure. The Standby at takes over.