Apex domains cannot have CNAME records.
Question and response
Question
dig ifx.net.co. NS
Answer
ifx.net.co. 4 NS ns0.ifxnetworks.co.
ifx.net.co. 4 NS ns1.ifxnetworks.co.
ifx.net.co. 4 NS ns1.ifxnetworks.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0