Apex domains cannot have CNAME records.
Question and response
Question
dig tigo.bo. NS
Answer
tigo.bo. 2 NS dns1.wimaxtigo.bo.
tigo.bo. 2 NS dns2.wimaxtigo.bo.
Authority
The response has no authority records.
Additional
dns1.wimaxtigo.bo. 2 A 200.73.97.94
dns2.wimaxtigo.bo. 2 A 190.104.14.94
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0