Set up nginx and DNS to subdomains on the same IP?

Question

Nginx

I want to make two domains:
fosss.ru
auth.fosss.ru

In nginx, I configured the config for two servers, but how to configure dns if both sites are on the same IP?

Answer 1

In nginx, I configured the config for two servers

I believe that all the same, on two different hosts, and not a server

but how to set up dns if both sites are on the same IP

assign one IP to both domains via A-records
your captain obvious