Active Directory Basics: Demonstrate Your Skills

Dark_Knight666​ That is the correct Domain! After you hit OK it should ask for the Credentials then say welcome to the ad.techcompany.local domain. 

Maybe it needs the DNS server added. I used the COMP-HYDRA tab. Try going to Control Panel > Network and Internet > Network and Sharing Center > Connections: Ethernet 

In the Ethernet Status window, click the Properties button. In this window, locate the Internet Protocol Version 4 (TCP/IPv4) option. Select it and click on the Properties button.

In the IPv4 Properties window, select Use the following DNS server addresses.

Enter the IP address of the Domain Controller in the Preferred DNS server field, and click the OK button to close the window, saving the changes.

After updating the DNS, you're ready to update the domain of the machine.
I also used the COMP-HYDRA tab for this step and I accessed it this way:
Open File Explorer, right-click This PC, and select Properties.

In the System Properties window, click the Change settings hyperlink in the Computer name, domain, and workgroup settings section. (Bottom Right of window).

Click the Change button to rename this computer or change its domain or workgroup.