HSRP: Hot Standby Router Protocol, rebuilt from the Computer Networks section handout as an interactive lesson. It covers what we will cover, the default gateway is a single point of failure, what hsrp is, active and standby routers, what an hsrp group keeps track of, one address the hosts never have to change, who becomes the active router, preemption decides what happens after a recovery. The lesson includes 5 interactive simulators you can click through directly in the slides.