Apex domains cannot have CNAME records.
Question and response
Question
dig mdc.edu. NS
Answer
mdc.edu. 5 NS ns1-04.azure-dns.com.
mdc.edu. 5 NS ns2-04.azure-dns.net.
mdc.edu. 5 NS ns3-04.azure-dns.org.
mdc.edu. 5 NS ns4-04.azure-dns.info.
Authority
The response has no authority records.
Additional
ns4-04.azure-dns.info. 4 A 208.84.5.4
ns4-04.azure-dns.info. 4 AAAA 2620:1ec:bda:700:0:0:0:4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0