ex2.gs.sits.pro has no CNAME records.
Question and response
Question
dig ex2.gs.sits.pro. NS
Answer
The response has no answer records.
Authority
gs.sits.pro. 149 SOA sits.pro. tech.sits.pro. 2023111742 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0