You have selected a mapped network to do a test failover. This network can be either a production network or can be connected ...

You have selected a mapped network to do a test failover. This network can be either a production network or can be connected to one of your production networks. 
Ensure that your primary virtual machines are shut down before your proceed. Otherwise two copies of the same virtual machine would be running at the same time. 
Note that all the changes made in the virtual machines during a Test Failover are lost when the Test Failover is completed.