A、The cypto isakmp keepalive command is used to configure the Stateful Switchover （SSO）protocol

B、Reverse Route Injection （RRI） is configured on at the remote site to inject the central sitenetworks

C、Each Hot Standby Routing Protocol （HSRP） standby group has two well-known MACaddresses and a virtual IP address

D、The cypto isakmp keepalive command is used to configure stateless failover