> Yes, many. Like running 2 different servers for the same protocol.
> Dependent on the sender address, the input firewall rules can redirect
> the incoming session to a certain port. For example: DNS request from
> the outside world: use port 53, DNS request from internal hosts: use a
> different server on port 5353.
I did not think of that and it's nice. You can do split brain DNS on
just one host without relying on an internal server that may be down.
Julio