Apex domains cannot have CNAME records.
Question and response
Question
dig azure-dns.net. NS
Answer
azure-dns.net. 5 NS ns2-04.azure-dns.net.
azure-dns.net. 5 NS ns2-03.azure-dns.net.
azure-dns.net. 5 NS ns2-01.azure-dns.net.
azure-dns.net. 5 NS ns2-02.azure-dns.net.
Authority
The response has no authority records.
Additional
ns2-01.azure-dns.net. 5 A 150.171.21.1
ns2-02.azure-dns.net. 5 A 150.171.21.2
ns2-03.azure-dns.net. 5 A 150.171.21.3
ns2-04.azure-dns.net. 5 A 150.171.21.4
ns2-01.azure-dns.net. 5 AAAA 2620:1ec:8ec:700:0:0:0:1
ns2-02.azure-dns.net. 5 AAAA 2620:1ec:8ec:700:0:0:0:2
ns2-03.azure-dns.net. 5 AAAA 2620:1ec:8ec:700:0:0:0:3
ns2-04.azure-dns.net. 5 AAAA 2620:1ec:8ec:700:0:0:0:4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0