In the event of a machine fault, feasible machine changes have to be reviewed by the operation scheduling and dispatching to avoid remarkable delays. In this approach, this is achieved by an automated identification of alternative machine tools and a reliable validation. First, a capable machine that satisfies the requirements of the NC program is searched within an ontology. Therefore, the ontology contains a description of all relevant characteristics of specific machine tools and expert rules to derive provided capabilities. Second, the NC program is validated on a virtual machine tool to ensure its accuracy.