You are designing a strategy to allow internal users in Dallas to resolve domain names.  What are three possible ways to achieve the goal？（）

• A、 Configure the internal DNS server to have a root zone.
• B、 Configure the Dallas DNS server to use the default root hints.
• C、 Configure the Dallas DNS server to forward all request for the external namespace to the external DNS server.
• D、 Create a caching-only DNS server on the perimeter network.
• E、 Create a stub zone for the external namespace on the Dallas DNS server.