If you are referring to the actual device configuration for the operation of the device such as those found in routers and switches then Discovery will not save them out-of-the-box. It is possible to capture the configuration of these devices and save into the CMDB including the ability to track changes but this would be all customizations that you would need to do. See documentation below for some information:
https://docs.servicenow.com/bundle/kingston-it-operations-management/page/product/discovery/concept/tracked-config-files.html
