Apex domains cannot have CNAME records.
Question and response
Question
dig signaturit.com. NS
Answer
signaturit.com. 5 NS jean.ns.cloudflare.com.
signaturit.com. 5 NS adam.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0