Apex domains cannot have CNAME records.
Question and response
Question
dig combrcloud.com.br. NS
Answer
combrcloud.com.br. 1 NS pat.ns.cloudflare.com.
combrcloud.com.br. 1 NS justin.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
pat.ns.cloudflare.com. 4 A 108.162.192.139
pat.ns.cloudflare.com. 4 A 172.64.32.139
pat.ns.cloudflare.com. 4 A 173.245.58.139
justin.ns.cloudflare.com. 4 A 108.162.193.187
justin.ns.cloudflare.com. 4 A 172.64.33.187
justin.ns.cloudflare.com. 4 A 173.245.59.187
pat.ns.cloudflare.com. 4 AAAA 2606:4700:50:0:0:0:adf5:3a8b
pat.ns.cloudflare.com. 4 AAAA 2803:f800:50:0:0:0:6ca2:c08b
pat.ns.cloudflare.com. 4 AAAA 2a06:98c1:50:0:0:0:ac40:208b
justin.ns.cloudflare.com. 4 AAAA 2606:4700:58:0:0:0:adf5:3bbb
justin.ns.cloudflare.com. 4 AAAA 2803:f800:50:0:0:0:6ca2:c1bb
justin.ns.cloudflare.com. 4 AAAA 2a06:98c1:50:0:0:0:ac40:21bb
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0