This tab allows you to control how DNS is handled by the server. If all of the DNS zones are to be hosted by other servers and you do not want this one to handle zone delegations, which would be the process of telling your registrar which DNS servers are authoritative for your domain name, you could select to set up the server as a Slave DNS server here.
HostGator already allows users to manage their own DNS settings; so whichever settings exist are only default settings. By default, the majority of DNS zones will be setup as the Master type. If they are not, then be sure to switch the DNS service mode back into doing so.
For information on how to toggle your server between Master and Slave DNS, please refer to the following information directly from Parallels:Performance in Plesk