Apex domains cannot have CNAME records.
Question and response
Question
dig webmastercolombia.net. NS
Answer
webmastercolombia.net. 5 NS ns1.webmastercolombia.net.
Authority
The response has no authority records.
Additional
ns1.webmastercolombia.net. 5 A 38.156.13.2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0