Windows dns an unknown error occurred while validating the server
If no external forwarder servers are specified it would then use the root hints servers.
My recommendation here is to use one or more external forwarders on these servers.
In most cases, this error occurs because the SQL Server service is stopped.
The Root Hints servers for l.& m.had unknown IP addresses.
The following additional errors can appear with The user does not have permission to access the data source.
If you are using a SQL Server database, verify that the user has a valid database user login.
Because they are not authorative for any domain as they do not operate as Top Level Domain (TLD) name service Root hint serves are authorative servers operated by various bodies. is operated by ICANN and j.is operated by Verisign.
These are hosted on multiple redundant servers published using anycast routing. If you look at the nslookup result you will see the difference.If the error also includes "No such host is known", it indicates that the Analysis Services server is not available or is refusing the connection.