Apex domains cannot have CNAME records.
Question and response
Question
dig t3.se. NS
Answer
t3.se. 4 NS ns2.telecom3.net.
t3.se. 4 NS ns4.telecom3.net.
t3.se. 4 NS ns1.telecom3.net.
t3.se. 4 NS ns3.telecom3.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0