Hello everyone, 1. I installed ISP Config 3 on Debian 9 according to: https://www.howtoforge.com/tutorial/ispconfig-3-automated-installation-on-debian-9/ 2. I added DNS Zone as in attachment ss1. I also added a page in the tab "Sites" 3. When to change the DNS domain in OVH. I get an error and the domain stays on OVH's default DNS. DNS adds according to created in ISPConfig. Sorry, but I'm just learning administration and ISPConfig.
You missed adding a-records for the two ns records. When the name servers of a domain are subdomains of the same domain, then you must add the name servers as a-records too and you must add glue records as well. See also the guide from @Taleman about setting up a DNS server with ISPConfig: https://www.howtoforge.com/tutorial/setting-up-your-own-name-service-with-ispconfig/
