A dedicated IP is an IP with no port. It changes your server IP from (192.168.65.34:25582) to (220.127.116.11) an IP with no port.
A dedicated IP is not a domain. However, it is used for servers starting out that don't want a port. It is also used for connecting domains & subdomains to the Minecraft server.
A domain is a record like (myserver.net) or (coolminecraftserver.org). Domains can be brought right from billing.plox.host a .com domain start $12 a year. We recommend if you start a network you do get a domain.
A sub-domain is a sub-record of your actual domain. If you own the domain (xylemnetwork.net). You can make a subdomain as (play.xylemnetwork.net) & (mc.xylemnetwork.net). You can make as many DNS records as you want for free. However, the end of the domain needs to be the same as the original domain. (.xylemnetwork.net) - The star represents anything you can place as the subdomain.
A sub-domain is generally used for servers for players to join. You could use (mc.xylemnetwork.net) for players to join your server if you own the domain. We can assist you in the setup progress.
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