We have a simple DAG setting with two sites(connected by vpn) and each site has only one exchange 2013. All the active mailboxes are in site A and the other copies are in the server in site B. The witness server is in Site A as well. We would like to simulate a failover by unplugging the network cable or power off the server holding the active mailboxes and see if everything including webmail, outlook and mobile devices can still function properly. Please tell me if anything I need to check or change before I perform this task. Thanks in advance