There are two Unix server A and B acting as a reverse proxy server.
Both the server A and B Natted with public IP to C and D respectively on Cisco ASA 5540 firewall.
The Public IP C and D got registered in public DNS server for Domain name registration using round robin method.
Now the requirement is if the server A goes down will the firewall Cisco ASA automatically redirect the whole traffic towards B server? This is something load balance support providing on Cisco ASA firewall.