Primary nameserver is listed
soa.mname-listed
The MNAME names the primary — the server secondaries pull from and the target of dynamic updates.
A longer write-up of this check has not been published yet. The report itself shows the raw evidence behind every result, which is usually the fastest way to see what was measured.
Run this check on a domain
Primary nameserver is listed is one of 49 checks in every report, alongside delegation, mail authentication, TLS and registration.