Local NS Matches Whois
Checks that the name servers defined in the whois record match those given by name servers themselves.
The domain name registrar allows you to specify your authoritative name servers in the Whois system (called the root record). These name servers are how a web browser turns a domain name into an IP address. An authoritative name server can be queried using the DNS system and they should (hopefully) reply with themselves if you ask for the name servers of a domain. This is called the local record.
If the name servers in the Whois system and the DNS system do not match (root does not match local), this test will indicate that there is a problem. There are two likely reasons. Either your authoritative name servers are misconfigured and giving bad answers, or the root record has been set to a recursive name server by mistake.