From where we can find the Available Fields for any CI type within Out of Box features. Also looking to know, if we can have OS fields for CMDB_CI_netgear class as per OOB functionality.
Look at the class manager. Custom fields will begin with a u_ column name OS fields do not come out of the box on cmdb_ci_netgear. The OS fields are defined the computer class which is not a parent of network gear.
