Apex domains cannot have CNAME records.
Question and response
Question
dig cloudlink.pt. NS
Answer
cloudlink.pt. 5 NS lara.ns.cloudflare.com.
cloudlink.pt. 5 NS sean.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0