Domain names for virtual machines on the internets?

Question

Domain Name System

Help me to understand. The situation is as follows:
1. I buy 5 domain names from a registrar.
2. There is Windows Server 2012 and hyper-v
3. I raise 5 virtual machines.
4. One channel with statics (one external ip)
4. You need to assign a domain name to each virtual machine, so that you can get to them from the Internet at the address virt1.ru virt2.ru, etc.
How does this process work? And then you don’t want to climb into the water without knowing the ford :)

Answer 1

In such a situation (one external IP), in order to access the web servers of these virtual machines, you need to install NGINX in reverse proxy mode in between, it will look to the outside world on this white IP and on ports 80-443, and respond to all external requests and, depending on the domain name that comes to it, it will proxy traffic to the desired VDS.
If you need to set one server on one port, another server on the second port, and a third on the third, then DNAT will help you.
In both cases, all A records in the DNS go to one IP.

Answer 2

OK thanks, very comprehensive answer with insight. And if not http, but let's say udp traffic on port 9091, or any other service.