Apex domains cannot have CNAME records.
Question and response
Question
dig chacaltaya.edu.bo. NS
Answer
chacaltaya.edu.bo. 4 NS ns1.cloudns.net.
chacaltaya.edu.bo. 4 NS ns2.cloudns.net.
chacaltaya.edu.bo. 4 NS ns3.cloudns.net.
chacaltaya.edu.bo. 4 NS ns4.cloudns.net.
Authority
The response has no authority records.
Additional
ns2.cloudns.net. 4 A 5.161.86.199
ns2.cloudns.net. 4 AAAA 2a01:4ff:f0:94da:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0