Hi,
this post describes the command line to get a list of all subnets for an Active Directory Site. The ds* commands are part of the Active Directory tools on Server and of RSAT Tools on Windows 7-10.
Search for a site
D:\> dsquery site -desc *mySite*
Or simple list all sites
D:\> dsquery site ... "CN=mySite,CN=Sites,CN=Configuration,DC=mySubDomain,DC=Domain,DC=org" ...
Or get the sitename of your computer
D:\> nltest.exe /DSGETSITE
And list all subnets
dsquery subnet -site "mySite"
Michael