I'm trying to setup an Active Directory network on Server 2012 R2, and want AD's DNS to only be used internally (Ex: domain-controller.company.com) as well as some records that need both internal and external accessibility (Ex: mail.company.com) that use internal IP's on the internal network and finally some records that only need external access.

The only solutions i have been able to think of, or look up are to either use a sub domain that handles all internal records, and use the plain company.com domain for all external records. These both seem to mean i have to manage two DNS servers separately. Is either of these the best ways or am i messing up somewhere?