I came across a customer site Windows DNS server that has it's external domain in a forward lookup zone on the AD server. There are some A and CNAME records here that we really don't want to be public. I'm wondering if we can configure DNS to point upstream to their SOA if it doesn't have an answer to a query for this domain, say searching for autodiscover.domain.com.
The upstream is a BIND DNS controlled by a web hosting company. I don't want to transfer zones and overwrite the static entries here, just reach out upstream if we don't know.
Is this possible? what's the mechanism? It's not really a split-DNS. I modified the SOA record but it doesn't do a recursive query upstream if it doesn't know.