Active-Passive Redundancy is a high availability mode of operation whereby two or more identical instances of the same network device or appliance operate simultaneously but only instances marked as active serve client requests.

If an active instance goes offline, passive instances begin to operate as active nodes servicing requests.

Mechanisms such as Virtual Router Redundancy Protocol (VRRP) along with floating IPs can be used to facilitate seamless network endpoint failover among the active-passive redundant instances.