You cannot set a CNAME record for a root domain (e.g., nic.example) because that would break RFC 1034 section 3.6.2, which states,
If a CNAME RR is present at a node, no other data should be present; this ensures that the data for a canonical name and its aliases cannot be different.
You can’t do this for nic.example because nic.example will also have NS records to make it work which breaks the rule that no other data should be present.
You can have a CNAME record for
www.nic.example because this is not the root domain, and therefore it is easy to have no other data present for it.
The only ways to get around this are to either
- use the www prefix, or
-
use an A (and/or AAAA) record and have the web-server handle the request accordingly