Lets say you are running a domain X, but want your internal DNS server to handle requests for both domain X and domain Y such that if machine1.X resolves to a.b.c.d, that machine1.Y would resolve to the same IP address?
Basically we would like to have a single master set of DNS records, but have a second domain which had all the same records. We're in the midsts of doing a migration, and it would be great if we didn't have to remember to update both sets of domain records all the time.
I've never tried this myself, but it may be possible to solve your problem using a DNAME record in order to alias an entire domain. In RFC 6672 it is defined thus:
According to this link it is an option also in Windows DNS:
You are not writing if the DNS domain(s) is the base of an AD too, or if it is just a DNS. I have no idea how an AD aliased in this way would respond. As a pure speculation one may also have to add a new UPN for the domain alias in the 'AD Domains and Trusts' tool. Another possibility is of course that the AD might totally freak out when called through its DNS aliased name, even if it has the alternate UPN in place.
Nope. You can do this either manually (as you fear) or script your DNS additions so that any A or CNAME records get added to both zones.
You could also script something to dump all A and CNAME records from both domains, merge them into a single list, and then push that into both domains. If this is a long project, you may need to do this a few times.