Hi,
this is not a Training and Certification question in my eyes. So maybe you should better look for a DNS Technet Forum.
I would simply install a local DNS client who is responsible for all requests and is caching. That way not all requests must be sent out of the local lan. But on the other side: DNS is not much traffic. It is normaly just a udp packet with the request and
a udp packet with the answer. TCP is only used for zone updates and such stuff.
With kind regards,
Konrad