So we wish to host some pages on a new server w/ apache2, and embed some of our old content & functionality from another server w/ lighttpd in an iframe. I'm looking at this configuration from the apache docs (http://httpd.apache.org/docs/2.2/vhosts/examples.html#page-header) under "Using Virtual_host and mod_proxy" together.

<VirtualHost *:*>
ProxyPreserveHost On
ProxyPass / http://192.168.111.2/
ProxyPassReverse / http://192.168.111.2/
ServerName hostname.example.com
</VirtualHost>

The only issue is that I want to proxy only on a subdomain, or even better, if I can keep the top domain and proxy only if the url contains a particular path ie. "/myprocess.php". So in essence the DNS will point to the apache2 as the "master router".