Apex domains cannot have CNAME records.
Question and response
Question
dig sectigo.com. NS
Answer
sectigo.com. 5 NS ns1.as48447.net.
sectigo.com. 5 NS ns2.as48447.net.
sectigo.com. 5 NS ns3.as48447.net.
Authority
The response has no authority records.
Additional
ns1.as48447.net. 5 A 91.199.212.50
ns2.as48447.net. 5 A 91.209.196.50
ns3.as48447.net. 5 A 91.212.12.50
ns1.as48447.net. 5 AAAA 2a0e:ac00:c7:d432:0:0:5bc7:d432
ns2.as48447.net. 5 AAAA 2a0e:ac00:d1:c432:0:0:5bd1:c432
ns3.as48447.net. 5 AAAA 2a0e:ac00:d4:c32:0:0:5bd4:c32
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0