Apex domains cannot have CNAME records.
Question and response
Question
dig fp-sign.com. NS
Answer
fp-sign.com. 5 NS pns02.dcsix.net.
fp-sign.com. 5 NS pns01.dcsix.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0