Log in to the control panel as admin.

Suppose we have two IPs:  

Go to "WEB → Domains "


Create a default domain in your admin account, for example example example.com

Go to "DNS ". Create a domain name and specify the primary IP


Click Advanced Options and create two NS entries

Record : ns1  
Type: A  
IP or Value: (i.e. main server ip)  

In the same way, we create a second NS

Record : ns2  
IP or Value: (your extra ip)  

The domain registrar, write the following data for your domain: example.com

NS1 ns1.example.com IP  
NS2 ns2.example.com IP  

After this you can write in all domains
as in the panel and at the registrar.

Updated Sept. 4, 2019