This topic should not be in developer help, but I’ll give you some advice anyways.

You want to run your server with ProxyDHCP enabled. This detects PXE boot requests on the network, allows the computers to get an IP address from the real DHCP server but get PXE boot details from your fog server.

I have heavily modified the articles on the wiki with my experience using Ubuntu 10.04 LTS and Fog 0.32. The article title is
[SIZE=6][B][URL=‘http://www.fogproject.org/wiki/index.php?title=Using_FOG_with_an_unmodifiable_DHCP_server/_Using_FOG_with_no_DHCP_server’][SIZE=4]Using FOG with an unmodifiable DHCP server/ Using FOG with no DHCP server[/SIZE][/URL][/B][/SIZE]