I created a private DNS zone on GCP for ***redacted***.com, and added only a CNAME record for a subdomain that doesn't resolve any IP address, subdomain.***redacted***.com. That's all. There is no A record or something else. Under these circumstances, I expected to see NXDOMAIN when I queried the A record, however the DNS server returned NOERROR. Why?
On the other hand, when I queried some FQDNs with the same conditions above, I observed that NXDOMAIN was returned as the response, instead of NOERROR.
I want to reproduce the same behaviour (returning NXDOMAIN) in Google Cloud DNS. How can I achieve this?