DRb server does not accept remote access

We want to use rails in a load balanced environment - i.e. the same
application is load balanced on 2 different servers. The Aaf DRb Server
should only run on one of the machines but serve both. I thought, that
would be easy to accomplish using the host: domain.com setting in
ferret_server.yml. For some reason, the DRb server only listens on the
localhost loopback interface, remote requests are not accepted.

What is it, that I am overlooking?

Thanks, Bernd Eickhoff