How to forward a subdomain to another Domain via DNS?

[MxAgent]

Hey,
i want to forward subdomain eg. "demo.mydomain.de" to another Domain Name eg."demo.dyndns.org" using DNS or whatever. But not only the HTTP-Port 80. I want to forward ALL Ports (mainly 80, 21) to the target-Domain. How can I realize that using Plesk or the unix-system behind plesk?

Help requiered!

Greetings from Germany,

Fabian Golle
Micronax.de

 

[Brujo]

with DNS for example:
Plesk > Domains > DNS Settings > Edit resource record of subdomain