When Parallels Plesk Panel is used in conjunction with the Cisco PIX 501 or ASA 5505 hardware firewall, two processes may be affected: the external resolution of domains while running DNS and the mapping of domain IP addresses through the firewall.
To ensure DNS compatibility between your Cisco PIX 501 or ASA 5505 hardware firewall and Parallels Plesk Panel, see Parallels Plesk Panel DNS Configuration.
When the Cisco PIX 501 or ASA 5505 hardware firewall is added to a network, the firewall inherits the public IP addresses of the domains and the domains are assigned new, private IP addresses. To reconfigure domains to their new address through Parallels Plesk Panel, see Configuring IPs in Plesk with a Hardware Firewall.