Apex domains cannot have CNAME records.
Question and response
Question
dig commercial.cgocable.net. NS
Answer
commercial.cgocable.net. 5 NS ns3.cgocable.net.
commercial.cgocable.net. 5 NS ns4.cgocable.net.
commercial.cgocable.net. 5 NS ns1.cgocable.net.
Authority
The response has no authority records.
Additional
ns4.cgocable.net. 5 A 24.226.1.46
ns4.cgocable.net. 5 AAAA 2001:1970:c06e:c0:0:0:0:46
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0