Hello Ajith
The order of operation depends on if the NAT involved is source NAT or destination NAT. Specifically:
For ASA versions before AND after 8.3 with SOURCE NAT, the order of operation does NOT change. That is:
1 Routing, 2 Inbound ACL, 3 NAT
For ASA versions BEFORE 8.3 and DESTINATION NAT, the order of operation is as follows:
1 ACL 2 Destination NAT 3 Routing
For ASA versions AFTER 8.3 and DESTINATION NAT, the order of operation is as follows:
1 Destination NAT/Partial routing* 2 ACL
*Partial routing refers to the determination of the exit interface based on the NAT rule.
I hope this has been helpful!
Laz