New Domain Controller with DNS in Windows has forwarders setup

Solution 1:

This does appear to be expected behavior, and it occurs when you create your domain controller.

DNS forwarders are auto-populated when the domain controller is promoted, according to a set of rules that's ill-documented by Microsoft, but that the fellow at the linked page seems to have enumerated nicely. I checked, and the auto-population behavior in Server 2012 R2 seems to be unchanged from Server 2008 R2. The only official word from Microsoft that I've been able to find on the subject is this Technet blog post.

It does makes sense, at least as far as copying external DNS forwarders - you presumably would want the same ones for all your domain controllers, or at the very least, would want all your domain controllers to have some external forwarder, so that your clients can perform DNS lookups for external domains.