Which additional active/standby failover feature was introduced in Cisco ASA Software Version
8.4?
A.
HTTP stateful failover
B.
OSPF and EIGRP routing protocol stateful failover
C.
SSL VPN stateful failover
D.
IPsec VPN stateful failover
E.
NAT stateful failover
Explanation:
http://www.cisco.com/en/US/docs/security/asa/asa84/configuration/guide/ha_overview.html#wp10
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Stateful Failover
When Stateful Failover is enabled, the active unit continually passes per-connection state
information to the standby unit. After a failover occurs, the same connection information is
available at the new active unit. Supported end-user applications are not required to reconnect to
keep the same communication session.
In Version 8.4 and later, Stateful Failover participates in dynamic routing protocols, like OSPF and
EIGRP, so routes that are learned through dynamic routing protocols on the active unit are
maintained in a Routing Information Base (RIB) table on the standby unit. Upon a failover event,
packets travel normally with minimal disruption to traffic because the Active secondary ASA
initially has rules that mirror the primary ASA. Immediately after failover, the re-convergence timer
starts on the newly Active unit. Then the epoch number for the RIB table increments. During re
convergence, OSPF and EIGRP routes become updated with a new epoch number. Once the
timer is expired, stale route entries (determined by the epoch number) are removed from the table.
The RIB then contains the newest routing protocol forwarding information on the newly Active unit.