Question
DynDNS is in use to forward dynamic IP address to the server.
How to set up the system to use dynamic name instead of an iP in Plesk?
Answer
Plesk doesn't support DynDNS.
It is recommended to use static IPs for all domains on the server.
As it is not implemented in Plesk, vote for this feature at the User Voice: Dyn DNS request.
The top-ranked suggestions are likely to be included in the next versions of Plesk.