Thanks for your help...
I just bought a Virtual Private Server and I want to configure my website and the DNS Server on the same server and of course IP.
I created a DNS Zone "domain.com", after I finished, a SOA record and NS record was added by default. Then I created the A record that points to the server IP 204.93.156.XXX.
The NS record added by default has as FQDN the server name and its IP address
print-screen of configuration
I have read that I should have two NS records with the format
ns1.domain.com -> IP
ns2.domain.com -> IP
But in my case the first one is FQDN -> IP
what should be the second on ns2.domain.com -> IP
If I do this it gives me an error
"IP for this server cannot be found"
I'm new to the configuration of DNS