My kid wanted mc.ourdomain.com instead of an ip with a port stuck on the end, and I managed to do it wrong twice before it worked.
The two options are simple once you see them: 1. an A record pointing the subdomain at the server ip, which only works if the server is on the default port 25565, or 2. an SRV record, which is the one that carries the port, so \_minecraft.\_tcp.mc as the name and the port inside the record itself. Most dns interfaces want those underscores exactly like that and will happily accept a name that never resolves.
Two gotchas. The cloudflare proxy has to be off, the orange cloud breaks a minecraft subdomain because none of this is http. And the SRV target has to be a hostname that itself resolves, not an ip, so you still need an A record underneath it.
Does anyone bother with a separate subdomain per world, or is that overkill for four players?
Source: r/SiteManagement · by /u/emilmarek