Apex domains cannot have CNAME records.
Question and response
Question
dig azure-dns.com. NS
Answer
azure-dns.com. 5 NS ns1-01.azure-dns.com.
azure-dns.com. 5 NS ns1-04.azure-dns.com.
azure-dns.com. 5 NS ns1-03.azure-dns.com.
azure-dns.com. 5 NS ns1-02.azure-dns.com.
Authority
The response has no authority records.
Additional
ns1-01.azure-dns.com. 5 A 13.107.236.1
ns1-02.azure-dns.com. 5 A 13.107.236.2
ns1-03.azure-dns.com. 5 A 13.107.236.3
ns1-04.azure-dns.com. 5 A 13.107.236.4
ns1-01.azure-dns.com. 5 AAAA 2603:1061:0:700:0:0:0:1
ns1-02.azure-dns.com. 5 AAAA 2603:1061:0:700:0:0:0:2
ns1-03.azure-dns.com. 5 AAAA 2603:1061:0:700:0:0:0:3
ns1-04.azure-dns.com. 5 AAAA 2603:1061:0:700:0:0:0:4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0