Apex domains cannot have CNAME records.
Question and response
Question
dig firmasoyou.ivcert.net. NS
Answer
firmasoyou.ivcert.net. 2 NS ns-514.awsdns-00.net.
firmasoyou.ivcert.net. 2 NS ns-1592.awsdns-07.co.uk.
firmasoyou.ivcert.net. 2 NS ns-292.awsdns-36.com.
firmasoyou.ivcert.net. 2 NS ns-1341.awsdns-39.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0