SQL Server Linked Server Inventory and Validation

Within authorized scope, use sqlcmd to inventory linked-server definitions on a reachable SQL Server instance and optionally run a fixed read-only SELECT @@VERSION through an existing approved linked server. The same authenticated workflow can run from a non-internal host only when the source SQL endpoint is explicitly Internet-reachable and the operator has authorized network access and credentials; this does not imply that SQL Server endpoints are generally Internet-accessible. These checks validate configuration and the current security context only; they do not demonstrate or execute operating-system commands.