At Settings > Nameserver sets you can define a set of nameservers so that the customer can easily select it when configuring domains, so he doesn't have to write each nameserver everytime when ordering a domain.
You can also restrict the nameserver set to a certain domain integration, so it is going to be available only for the domains from that integration, by selecting it at the "Domain Module" dropdown:
If no module is selected, than this nameserver set is going to be available globally.
