When you need to bring a virtual machine on a domain and test, for ex: when doing firewall testing you can do it as below:

1. Start the VM and go to its settings.
2. Change the network adapter to select, VMnet or NAT and set it
3. Now get into your VM, by turning it on and goto the settings of you network connections.
4. Right click, and then click properties
5. Change its IP address to point, it to something under your domain ip addresses
6. Eg: If you all computers inside your domain has 200.x.x.x, you can set the ip address as 200.2.3.4, something which doesnt clash with other VMs and local computers
7. Next we goto the DNS settings and set the default gateway and DNS server to the ip address of your domain server
8. For this your domain server must already be running.
9. Then right click on the my computer and select properties and then select change computer name
10. Here you will see a button to add to a domain.
11. Add the domain address here
12. It will ask for the password/username of the server
13. After entering it, if you restart the VM, your all set. The VM is on the domain.