Apex domains cannot have CNAME records.
Question and response
Question
dig fiber7.init7.net. NS
Answer
fiber7.init7.net. 5 NS ns1.init7.net.
fiber7.init7.net. 5 NS ns2.init7.net.
Authority
The response has no authority records.
Additional
ns1.init7.net. 5 A 213.144.129.2
ns2.init7.net. 5 A 212.55.195.90
ns1.init7.net. 5 AAAA 2001:1620:2777:0:0:0:0:2
ns2.init7.net. 5 AAAA 2001:8a8:21:4:0:0:0:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0