Before you create forest trusts between domains, it is important to verify that the Domain Name System (DNS) server in your environment is properly set up and configured to accept future trust relationships. Complete the tasks in this checklist in order. When a reference link takes you to a conceptual topic, return to this topic after you review the conceptual topic so that you can proceed with the remaining tasks in this checklist.
If there is a root DNS server that can be the root DNS server for both of the forest DNS namespaces, make it the root server by ensuring that the root zone contains delegations for each of the DNS namespaces. Also, update the root hints of all DNS servers with the new root DNS server.
If there is no shared root DNS server and the root DNS servers for each forest DNS namespace are running a Windows Server 2008 operating system, configure DNS conditional forwarders in each DNS namespace to route queries for names in the other namespace.
If there is no shared root DNS server and the root DNS servers for each forest DNS namespace are not running a Windows Server 2008 operating system, configure DNS secondary zones in each DNS namespace to route queries for names in the other namespace.