multiple shared hostings with just 1 public ip

Hi, I was reading about web proxy to have multiple web servers running behind nat with just 1 public ip.

my problem is how to get running multiple shared hosting servers with just 1 ip, because when you add a new domain to a one machine, it registers on the dns server of that machine.

supose that I have:

web proxy configuration i’ve found is useful if I use external dns servers pointing domains to my public IP, so the router can redirect the request to the correct web server if I only have i.e. 3 servers hosting only 1 domain per server. the problem I have is each server has it’s own dns server which have the registry of any of the domains hosted by that server.

i’m not sure if I’m planning this in the correct form in order to get everything working, but I supone the natural way to do it is to have independient machines running it’s own services.