How to configure secondary DNS?

I bought a dedicated server from a company and they give me a secondary DNS server:
Debian 8 64bit with
ISPConfig 3.0.5.4p8

I added my domain to that server and they told me I need to add this domain as a secondary DNS with option allow on my dedicated server.
So how I can configure secondary DNS?


What should I put in the bottom 2 fields? IP of the secondary DNS server? IP of my server? I don't have IP of the secondary server just it's domain: sdns2.ovh.net

 

https://www.howtoforge.com/how-to-run-your-own-name-server-with-ispconfig-3-and-fast-hosts