Apex domains cannot have CNAME records.
Question and response
Question
dig firedrake.org. NS
Answer
firedrake.org. 5 NS ns1.firedrake.org.
firedrake.org. 5 NS ns0.firedrake.org.
Authority
The response has no authority records.
Additional
ns0.firedrake.org. 5 A 212.110.173.52
ns1.firedrake.org. 5 A 78.46.68.84
ns0.firedrake.org. 5 AAAA 2001:41c9:1:404:0:0:0:52
ns1.firedrake.org. 5 AAAA 2a01:4f8:120:5343:0:0:0:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0