Apex domains cannot have CNAME records.
Question and response
Question
dig tigo.net.bo. NS
Answer
tigo.net.bo. 5 NS dns1.tigo.net.bo.
Authority
The response has no authority records.
Additional
dns1.tigo.net.bo. 5 A 200.73.97.94
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0