systeminfo

The Windows systeminfo command displays a lot of information! Use findstr to filter its output:

systeminfo | findstr /B /C:"OS Name" `
                        /C:"OS Version" `
                        /C:"System Type"

This can be used to semi-reliably determine if a machine is part of a domain.

systeminfo | findstr Domain

(Non-AD joined machines will almost always use WORKGROUP for the Domain, while AD-joined machines will often use a fully qualified DNS domain here.)