Apex domains cannot have CNAME records.
Question and response
Question
dig msn.com. NS
Answer
msn.com. 1 NS dns2.p08.nsone.net.
msn.com. 1 NS dns3.p08.nsone.net.
msn.com. 1 NS ns4-204.azure-dns.info.
msn.com. 1 NS dns1.p08.nsone.net.
msn.com. 1 NS ns2-204.azure-dns.net.
msn.com. 1 NS dns4.p08.nsone.net.
msn.com. 1 NS ns1-204.azure-dns.com.
msn.com. 1 NS ns3-204.azure-dns.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0