see the link for ASA reduntant config
also read the below.
This configuration provides a relatively inexpensive way to ensure that outbound Internet access remains available to users behind the security appliance. As described in this document, this setup may not be suitable for inbound access to resources behind the security appliance. Advanced networking skills are required to achieve seamless inbound connections
How can we configure the inbound reduntant for the outside users access to the inside servers.