you need to be allocated an i address by your isp
because if your server is running dns to get internet acces then the dhcp server is assigning to your in house network those ip addresses will not get you on the net as they are not members of your isp domain.

But if they give you a static for you server the you can allow your server to allocate to your clients thus makeing all your machines a member also you will need to point and url you own to the static ip you recieve from your isp........

hope that helps