Hyper-V Replica: primary and replica servers, replication frequency, recovery points, planned and unplanned failover, test failover

Hyper-V Replica is a built-in disaster recovery feature that asynchronously copies a VM from one Hyper-V host (the primary server) to another (the replica server), often in a different site. The replica VM stays off and receives changes; if the primary site fails, you start it. No shared storage, special hardware or cluster is required, and hosts can be in different domains when you use certificate authentication.