Apex domains cannot have CNAME records.
Question and response
Question
dig sundials.org. NS
Answer
sundials.org. 5 NS falcon.chezaubert.net.
sundials.org. 5 NS finch.chezaubert.net.
sundials.org. 5 NS dove.chezaubert.net.
sundials.org. 5 NS pelican.chezaubert.net.
Authority
The response has no authority records.
Additional
finch.chezaubert.net. 5 A 143.198.12.158
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0