The CDROM image was a firmware upgrade image from Dell (based on Linux). Mounting the image with iDRAC, it worked nicely. As one of the Servers had a dying iDRAC (Dell R320), I needed an USB stick.

Anyone who is 40 or under and raised as a user, rather than an expert, is unlikely to even remember MS-DOS. Let alone command-driven Unix. The point-and-click interface of Windows 3.0 dropped 20 years ...