V11 HA if heartbeat communication is lost = standby standby?

Hi Folks, Just studying for an exam, and a question is testing for situations for HA pair to go standby standby. I recall then v10 was fail to active if Heartbeat lost, but I thought V11 changed to standby standby. Can anyone clarify? And mention any other situations that could result in standby standby. (like vlan failsafe with action of standby)