About Host, Interface, and General Service Settings : About the DNS testing tool
  
About the DNS testing tool
The diagnostic tool at the bottom of the page helps troubleshoot common issues with Windows domain authentication when encrypted MAPI or SMB signing is used. Enter the fully qualified Active Directory domain name (usually your company’s domain name), and then run the test.
DNS testing tool showing results of a successful configuration
The test results section remains empty until you run the first test. After that, the most recent test results will appear. A shortened time stamp is shown on the left of each log line. Mouse over it to see the full time stamp. Some log lines may not have time stamps, as certain third-party applications generate the log data.
About host settings
DNS