Apex domains cannot have CNAME records.
Question and response
Question
dig marcom.com. NS
Answer
marcom.com. 5 NS ns2-05.azure-dns.net.
marcom.com. 5 NS ns3-05.azure-dns.org.
marcom.com. 5 NS ns4-05.azure-dns.info.
marcom.com. 5 NS ns1-05.azure-dns.com.
Authority
The response has no authority records.
Additional
ns2-05.azure-dns.net. 3 A 150.171.21.5
ns3-05.azure-dns.org. 3 A 204.14.183.5
ns4-05.azure-dns.info. 3 A 208.84.5.5
ns2-05.azure-dns.net. 3 AAAA 2620:1ec:8ec:700:0:0:0:5
ns3-05.azure-dns.org. 3 AAAA 2a01:111:4000:700:0:0:0:5
ns4-05.azure-dns.info. 3 AAAA 2620:1ec:bda:700:0:0:0:5
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0