All client computers on your company network run Windows 7 and are members of an Active Directory Domain Services domain

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All client computers on your company network run Windows 7 and are members of an Active Directory Domain Services domain named contoso.com.
Employees access the company intranet site at http://app.contoso.com.
The Test team must be able to access a new version of http://app.contoso.com before the site is in production.
You need to ensure that the Test team can access the new version of the site without affecting other employees' access to the current site.
What should you do?

A. Create a DNS record for app.contoso.com that specifies the IP address of the test server.
B. Create a Windows Firewall rule that blocks access to the IP address of the test server on the employees' computers.
C. Create a Windows Firewall rule that allows access to the IP address of the test server on the Test team's computers.
D. Add an entry to the Hosts file that specifies app.contoso.com and the IP address of the test server on the Test team's computers.