In order to setup your own custom nameservers there are a couple of steps you will need to work through:
1.) The first job will be to go to the control panel where you manage the DNS for the domain you wish to use. From the DNS panel you need to create 2 new A records (one for each of the new nameservers). You need to set the new A records for ns1.domain.com pointing to the IP 126.96.36.199 and then create a second A record for ns2.domain.com pointing to 188.8.131.52.
(in this example you would change domain.com with your actual domain name)
In Plesk the DNS tool is called ‘DNS settings’ and in cPanel this is called ‘Zone editor’.
Plesk DNS editor
cPanel DNS editor
1.) Once the A records have been created you then need to contact the domains registrar and ask them to create glue records for your new nameservers. To do this just send them a message and provide them with the new nameservers and corresponding IP addresses and ask them to create the glue records, this should be a straight forward process.
2.) The last step which we can do for you from here will be to add your new nameservers to the global list so that when you then try to update the client’s domains these new nameservers will be accepted.
3.) Once this is all set up please allow some time for the DNS to fully propagate.