I am using a nginx reverse proxy server. Behind the reverse proxy are 3 apache servers on 3 IP addresses
apache1 - 192.168.1.101 (4x vhost)
apache2 - 192.168.1.106 (1x vhost)
apache3 - 192.168.1.107 (1x vhost)
nginx - 192.168.1.105
apache 2 and apache 3 work great.
This is the nginx...