How does domain aliasing work?

[SolidSonicTH]

Basically what I want to do is create a way to route different subdomain hostnames to a single dynamic IP address that allow me to ensure I know what data is flowing in on which port for proper internal forwarding (so I could have something like a "plex.____.org" subdomain that would allow me to directly hit my Plex server from the web without using Plex's website, for instance).

The most direct way I can do this would be via updating several subdomains via DDNS to all point to the same IP as my primary domain but my router won't do that (I think I saw it's possible if I install custom firmware on it but I've yet to do that - although I'm probably going to do it anyway in order to also get at split-horizon DNS). However as I did some research it seems like domain aliasing could do this without needing to run anything on my end to facilitate it (just by mapping the aliases to point to the primary domain, at which point the traffic coming in on those subdomains is already tailored for the destination server on the inside of the network). Is this a correct interpretation of what domain aliases do or is my idea to use direct DDNS hostname registries the right way to approach this?

 

[RMerlin]

Update just one DDNS (for example myhome.dyndns.org). Then, create the aliases as this:

plex.mydomain.com CNAME myhome.dyndns.org
home.mydomain.com CNAME myhome.dyndns.org
etc...

You need one CNAME per subdomains you want to redirect.