When Toad for SQL Server is opened, even before a connection is made, it attempts connections to the server every second, which can cause Audit Failure errors in the Windows Event Log on the server.
There is a feature in Toad that tries to ping registered servers to detect their running status. It uses Windows accounts that Toad is running on. Therefore it may not get server statuses in some cases (in a more complex instance configuration).
You can turn off this feature in Tools | Options | Database | General | ”Poll service status in connection list” - set to unchecked.
This option will be set to unchecked state by default starting from v5.7 (next available version).
Therefore you are able re-register servers to a previous state and turn this option off.
CR98825 created to stop writing Failure Audit events to the Security log.
Regarding question marks next to the connections, they mean that Toad wasn’t able to get server status. As described above, it may occur on some servers settings or if a Windows user has no access under their Windows account