To make the Plesk's DNS server act as a secondary name server, perform the following steps:
1 - 1 - Logged in to Plesk, https://your domain name:8443.
2 - Go to Websites & Domains and click the domain name whose DNS settings you want to manage.
3 - Click DNS Settings.
4 - Click Master/Slave to switch DNS server mode.
5 - Click Add Record.
6 - Specify the IP address of the primary (master) DNS server.
7 - Click OK, and then click Update.
Repeat steps from 3 to 7 for each website that needs to have a secondary name server on your server.
