The Master Zone also known as Primary Zone in the DNS server is the read or write copy of the DNS database. This means that whenever a new DNS record is added to the DNS database either automatically or manually, it is actually written in the master zone of the DNS server. The records in the Master zone can be managed only from our interface.
Login in your account, click on the DNS zones [Add new] link, click on the Master zone box, enter the domain name (without www or http://) and click on the create button. You may want to choose only the servers you will add to the domain registrar or leave them all checked. You will be forwarded to the Records page of the DNS zone of your domain, there you will be able to add the records you need.
Create zone with NS records - this option is selected by default. It is the easiest way to create a Master DNS zone with NS records for all name servers, available for you.
Copy all records from other zone - this option is suitable, if you would like to copy all records of another DNS zone into your new one.
Create zone without any records - selecting this option will create a DNS zone without any NS records in it. You will have to manually add them afterwards.