Apex domains cannot have CNAME records.
Question and response
Question
dig n-v1.mx.microsoft. NS
Answer
n-v1.mx.microsoft. 5 NS ns1-82.azure-dns.com.
n-v1.mx.microsoft. 5 NS ns4-82.azure-dns.info.
n-v1.mx.microsoft. 5 NS ns3-82.azure-dns.org.
n-v1.mx.microsoft. 5 NS ns2-82.azure-dns.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0