For the fresh Parallels Business Automation - Standard installation, by default you have two Provider name servers grouped into one set - the default name servers set.
You can use the default name servers set or you can add more name servers and create more name servers sets.
It is possible to install and configure name servers directly from the Provider Control Center web-based interface.
The default name servers set can be selected in the Service Director - Domain Manager - Setup.
Name servers set are specified per Domain-Registration Hosting Plan.