Name: Internal Access to Webserver
Traffic Source: Internal (Network)
Traffic Service: HTTP
Traffic Destination: External (Address)
NAT mode: Full NAT
Destination: {IP of webserver in DMZ}
Destination: Service: leave blank
Source: DMZ (Address)
Source Service: Leave blank
Automatic packet filter rule: Check
Name: Internal Access to Webserver
Traffic Source: Internal (Network)
Traffic Service: HTTP
Traffic Destination: External (Address)
NAT mode: Full NAT
Destination: {IP of webserver in DMZ}
Destination: Service: leave blank
Source: DMZ (Address)
Source Service: Leave blank
Automatic packet filter rule: Check
I'd make a couple small changes:Name: Internal Access to Webserver
Traffic Source: Internal (Network)
Traffic Service: HTTP
Traffic Destination: External (Address)
NAT mode: Full NAT
Destination: {IP of webserver in DMZ}
Destination: Service: leave blank
Source: DMZ (Address)
Source Service: Leave blank
Automatic packet filter rule: Check
This is not recommended if you are using the HTTP/S Proxy. If you are, then you should use Barry's suggestion. If you're in "Transparent" mode, the DNS entry must be available to the client's browser. If in a non-transparent mode, the ASG must have the entry or a 'DNS request route' back to your internal DNS.
Cheers - Bob