Apex domains cannot have CNAME records.
Question and response
Question
dig exponential-e.net. NS
Answer
exponential-e.net. 5 NS auth0.exponential-e.net.
exponential-e.net. 5 NS auth1.exponential-e.net.
Authority
The response has no authority records.
Additional
auth0.exponential-e.net. 5 A 62.244.177.179
auth1.exponential-e.net. 5 A 62.244.176.178
auth0.exponential-e.net. 5 AAAA 2a00:1d40:ee:177:0:0:0:179
auth1.exponential-e.net. 5 AAAA 2a00:1d40:ee:176:0:0:0:178
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0