I tried to do something which I did not know is impossible at all (point a domain root to a CNAME entry). As I have many domains my idea was to maintain a single entry where I could switch the IP addresses easily and all domains with just a CNAME instead of A and AAAA should just take over the IPs from the single new entry.
Now I know that this is not possible. But during the path deSEC was providing me some misleading information. Maybe this could be changed. 
What I did:
- I had A, AAAA, MX, TXT and a NS record in place for domain.com which should become my central “management” place for the A and AAAA records
- I created a subdomain entry (e.g. web1.domain.com) with the relevant A and AAAA record. This was the entry I wanted to use as a reference in the CNAME entries for all other domains
- Then I replaced the A and AAAA records for domain.com with a CNAME pointing to web1.domain.com and got this error message:
RRset with conflicting type present at same subname: database (MX, NS, TXT). (No other RRsets are allowed alongside CNAME.) - So I started to remove MX, NS and TXT records and added them to my new subdomain entry instead.
- With no entries left on the root level for domain.com I tried to add the CNAME again getting this error message:
CNAME RRset cannot have empty subname.
Conclusion:
As it is not possible to have a CNAME with an empty subname (that was what I wanted to achieve on the domain root level not knowing it’s not possible) the last error message should be displayed always someone tries to add a CNAME with an empty subname. The other error messages checking against “competing” types should be skipped as they are misleading.
I hope I got this right – if not please tell me
PS: 100% human, 0% “AI”