Apex domains cannot have CNAME records.
Question and response
Question
dig hosteddmarc.dmarc-dns.com. NS
Answer
hosteddmarc.dmarc-dns.com. 5 NS ns-1887.awsdns-43.co.uk.
hosteddmarc.dmarc-dns.com. 5 NS ns-913.awsdns-50.net.
hosteddmarc.dmarc-dns.com. 5 NS ns-321.awsdns-40.com.
hosteddmarc.dmarc-dns.com. 5 NS ns-1206.awsdns-22.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0