You are a messaging professional. Your company uses a Microsoft Exchange Server 2003 messaging system. The company has a main office and two branch offices. A Microsoft Active Directory site and an Exchange routing group are configured for each office.

The three offices have the following Exchange Server 2003 computers:
+ 2 Back-end servers that are non-clustered
+ 1 dedicated routing group connector bridgehead server

The main office also has a dedicated bridgehead server for routing e-mail to and from the Internet. All Exchange Server computers are x86-based and run Microsoft Windows Server 2003 Release 2. The company plans to upgrade to a Microsoft Exchange Server 2007 messaging system. The company plans to implement high availability for Mailbox servers and message routing. The following Exchange Server 2007 computers will be deployed in each site:
+ 2 Cluster Continuous Replication (CCR) Mailbox servers
+ 2 Hub Transport server and Client Access Server computers

The company requires that you maintain an adequate test environment for pre-production testing of all changes and modifications to the Exchange messaging system.

The company has the following requirements for the test lab:
+ All production services must be adequately mirrored in the test environment.
+ Connectivity across WAN links must be mirrored, although replicating each location is not necessary.
+ The test environment must use the same code base as the production environment.
+ The test environment domain controllers and global catalog servers must not run Exchange Server 2007.
+ The test environment design must require the purchase of the fewest number of servers possible, without violating the other requirements.
+ The test environment will not be implemented until the deployment of Exchange Server 2007 computers is complete.

You plan to use two of the decommissioned Exchange Server 2003 computers as domain controllers and global catalog servers in the test environment. You need to create a plan for the implementation of the test environment.

Which action should you include in the plan to create a plan for the implementation of the test environment?