Apex domains cannot have CNAME records.
Question and response
Question
dig azure-dns.info. NS
Answer
azure-dns.info. 5 NS ns4-03.azure-dns.info.
azure-dns.info. 5 NS ns4-02.azure-dns.info.
azure-dns.info. 5 NS ns4-01.azure-dns.info.
azure-dns.info. 5 NS ns4-04.azure-dns.info.
Authority
The response has no authority records.
Additional
ns4-01.azure-dns.info. 5 A 208.84.5.1
ns4-02.azure-dns.info. 5 A 208.84.5.2
ns4-03.azure-dns.info. 5 A 208.84.5.3
ns4-04.azure-dns.info. 5 A 208.84.5.4
ns4-01.azure-dns.info. 5 AAAA 2620:1ec:bda:700:0:0:0:1
ns4-02.azure-dns.info. 5 AAAA 2620:1ec:bda:700:0:0:0:2
ns4-03.azure-dns.info. 5 AAAA 2620:1ec:bda:700:0:0:0:3
ns4-04.azure-dns.info. 5 AAAA 2620:1ec:bda:700:0:0:0:4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0