ns2.dns.pt has no CNAME records.
Question and response
Question
dig ns2.dns.pt. NS
Answer
The response has no answer records.
Authority
dns.pt. 300 SOA dns01.dns.pt. request.dns.pt. 2026030201 21600 7200 2592000 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0