The firewalls in an Active-Passive HA pair can be assigned
a
device priority value to indicate a preference for
which firewall should assume the active role. If you need to use
a specific firewall in the HA pair for actively securing traffic,
you must enable the preemptive behavior on both the firewalls and
assign a device priority value for each firewall. The firewall with
the lower numerical value, and therefore
higher priority,
is designated as active. The other firewall is the passive firewall.