That's a function of the firewall. It probably forwards requests to DNS entries to the proper machine, but if you give the IP address of the firewall itself it will try to resolve them to itself.
foo in your case will be a URL that maps to the machine your appserver is running on in the DNS table of the firewall.
That's a function of the firewall.
No, it isn't, but thanks for your reply.
I analysed the network traffic with wireshark and found that the problem is a wrong proxy configuration for IE. Accidentally, the corporate LAN segment containing the firewall is not contained in the list of direct connections.
Sorry for wasting everybody's time.