Apex domains cannot have CNAME records.
Question and response
Question
dig zoho.com.br. NS
Answer
zoho.com.br. 5 NS dns1.p03.nsone.net.
zoho.com.br. 5 NS dns2.p03.nsone.net.
zoho.com.br. 5 NS pdns90.ultradns.biz.
zoho.com.br. 5 NS dns4.p03.nsone.net.
zoho.com.br. 5 NS dns3.p03.nsone.net.
zoho.com.br. 5 NS pdns90.ultradns.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0