You want to know which domain you are currently connected to? There are 2 ways to figure out this.
Method 1
Right click on My Computer (or Computer) and select Properties. You will see the domain name here (as per below screenshot).
Method 2
Execute the command, nbtstat -a IP_ADDRESS,
C:\Users\Administrator>nbtstat -a 192.168.1.10
Primary LAN - SAP:
Node IpAddress: [192.168.1.10] Scope Id: []
NetBIOS Remote Machine Name Table
Name Type Status
---------------------------------------------
DOMAIN <00> GROUP Registered
MAC Address = 1C-B3-4T-J2-51-90
