Apex domains cannot have CNAME records.
Question and response
Question
dig bo. NS
Answer
bo. 5 NS ns.dns.br.
bo. 5 NS ns.nic.bo.
bo. 5 NS ns2.nic.fr.
bo. 5 NS anycast.ns.nic.bo.
Authority
The response has no authority records.
Additional
ns.nic.bo. 172301 A 166.114.1.40
anycast.ns.nic.bo. 146925 A 204.61.216.48
anycast.ns.nic.bo. 146925 AAAA 2001:500:14:6048:ad:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0