Apex domains cannot have CNAME records.
Question and response
Question
dig metrocom.com.pa. NS
Answer
metrocom.com.pa. 5 NS ns4.metrocom.com.pa.
metrocom.com.pa. 5 NS ns2.metrocom.com.pa.
metrocom.com.pa. 5 NS ns1.metrocom.com.pa.
metrocom.com.pa. 5 NS ns3.metrocom.com.pa.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0