Apex domains cannot have CNAME records.
Question and response
Question
dig colorado.net. NS
Answer
colorado.net. 3 NS ns1.vcn.com.
colorado.net. 3 NS ns3.vcn.com.
colorado.net. 3 NS ns2.vcn.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0