Apex domains cannot have CNAME records.
Question and response
Question
dig foilhat.io. NS
Answer
foilhat.io. 5 NS ns-240-b.gandi.net.
foilhat.io. 5 NS ns-85-c.gandi.net.
foilhat.io. 5 NS ns-155-a.gandi.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0