Assuming there are open connections through an active system's NAT and a failover occurs, by default, what happens to those connections? 

All open connections will be lost. 

All open connections will be maintained. 

The "Mirror" option must be chosen on the NAT and the setting synchronized prior to the connection establishment. 

Long-lived connections such as Telnet and FTP will be maintained while short-lived connections such as HTTP will be lost. 

All open connections are lost, but new connections are initiated by the newly active BIG-IP, resulting in minimal client downtime.