Apex domains cannot have CNAME records.
Question and response
Question
dig chatpro.pt. NS
Answer
chatpro.pt. 3 NS elmo.ns.cloudflare.com.
chatpro.pt. 3 NS mia.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
mia.ns.cloudflare.com. 5 A 108.162.192.200
mia.ns.cloudflare.com. 5 A 172.64.32.200
mia.ns.cloudflare.com. 5 A 173.245.58.200
elmo.ns.cloudflare.com. 5 A 108.162.193.163
elmo.ns.cloudflare.com. 5 A 172.64.33.163
elmo.ns.cloudflare.com. 5 A 173.245.59.163
mia.ns.cloudflare.com. 5 AAAA 2606:4700:50:0:0:0:adf5:3ac8
mia.ns.cloudflare.com. 5 AAAA 2803:f800:50:0:0:0:6ca2:c0c8
mia.ns.cloudflare.com. 5 AAAA 2a06:98c1:50:0:0:0:ac40:20c8
elmo.ns.cloudflare.com. 5 AAAA 2606:4700:58:0:0:0:adf5:3ba3
elmo.ns.cloudflare.com. 5 AAAA 2803:f800:50:0:0:0:6ca2:c1a3
elmo.ns.cloudflare.com. 5 AAAA 2a06:98c1:50:0:0:0:ac40:21a3
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0