Summary: Use a Windows PowerShell cmdlet from the ActiveDirectory module to check for the domain mode of your AD DS domain.
How can I easily find out the domain mode of my Active Directory Domain Services (AD DS) domain by using a Windows PowerShell cmdlet?
Use the Get-ADDomain cmdlet and select the domainMode property. It is also a good idea to select the DistinguishedName at the same time. This technique is shown here.
11:51 C:\> Get-ADDomain | select domainMode, DistinguishedName