How to create a custom nameserver in Plesk?
Newly created domain example.com in Plesk already has predefined NS records that looks like
ns2.example.com. Those records are generated based on DNS Template
If it is required create some custom name server for the domain, the NS and A records have to be configured, e.g.:
Browse to Home > Domains > example.com > DNS Settings and configure A, NS records in accordance to this article:
After that configure custom name server on the domain registrar's side according to the article How to configure name server for domain on registrar's side?
Note: If it is required to be done server-wide, specify NS servers in the Tools & Settings > DNS Template.
Then apply DNS Template Changes server-wide (Linux only) if required. Otherwise, new domains only are going to be updated.