Authoritative Name Servers

Checks that the name servers for this domain report that they are authoritative.

A name server turns domain names into IP addresses. There are two types of name servers: Recursive name servers and Authoritative name servers.

Recursive Name Servers

A recursive name server is the one that you set in your computer's settings and is how your computer looks up IP addresses for websites. This name server is often provided by your ISP or you may choose to use a public name server from companies like Google (8.8.8.8) or Cloudflare (1.1.1.1). These recursive name servers are not authoritative. When they get a query, they have to look it up by asking the authoritative name servers for the answers. Recursive name servers are entered into your computer as an IP address because if you entered a hostname, there would be no way for them to look up themselves.

Authoritative Name Servers

An authoritative name server is the one that holds the true answers to DNS queries. These servers are usually run by your hosting provider or domain name registrar. This is where you would go to set the IP address for your website and set other DNS records. Authoritative name servers are specified in the Whois and DNS systems as hostnames (ex: ns.example.com) which themselves need to be resolved into IP addresses.

The name server that is defined for the domain should respond to queries and state that it is the authoritative answer. If the name server does not claim to be authoritative, then there is a misconfiguration somewhere. Perhaps the name severs are configured incorrectly, or perhaps one of the name servers set for the domain is a recursive name server.