ASA active/standby does not support preemption, only active/active or multicontext mode does.
http://www.cisco.com/en/US/docs/security/asa/asa80/configuration/guide/failover.html#wp1048966
ASA active/standby does not support preemption, only active/active or multicontext mode does.
http://www.cisco.com/en/US/docs/security/asa/asa80/configuration/guide/failover.html#wp1048966