Apex domains cannot have CNAME records.
Question and response
Question
dig srv.cat. NS
Answer
srv.cat. 5 NS ns-1573.awsdns-04.co.uk.
srv.cat. 5 NS ns-1107.awsdns-10.org.
srv.cat. 5 NS ns-358.awsdns-44.com.
srv.cat. 5 NS ns-695.awsdns-22.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0