A Secondary IP Set is a set of one or more master name server IP addresses for a secondary DNS domain. A secondary DNS domain must have an IP Set applied to it at all times. You can modify or switch IP Sets if required. If the IP Set you want to use is not available, create a new one.
Step 1: Enter Managed DNS
At the top of the Control Panel, Click the DNS Menu and select Managed DNS from the drop-down.
Step 2: Choose your domain
Select a domain from the either the Recently Updated Domains box, or start typing the domain name in the text box on the “Select Domain” tab.
Step 3: Add the IP Set to the domain
Click on the IP Set drop-down menu to select another IP Set to assign to the domain. Then, click Submit