How to read out Dell Servicetag on Windows

1.) Open CMD.exe / Command Shell in Windows

2.) wmic bios get serialnumber

Taken from: https://www.dell.com/support/article/us/en/04/sln268357/how-to-locate-system-service-tag-using-command-prompt?lang=en

Dell Servicetag on Ubuntu

You can find out your Dell/Sun Servicetag on Ubuntu via:
sudo dmidecode -s system-serial-number