Apex domains cannot have CNAME records.
Question and response
Question
dig fth.tafjordconnect.net. NS
Answer
fth.tafjordconnect.net. 5 NS name1.mimer.no.
fth.tafjordconnect.net. 5 NS name2.mimer.no.
fth.tafjordconnect.net. 5 NS name3.mimer.no.
Authority
The response has no authority records.
Additional
name1.mimer.no. 4 A 213.184.200.110
name2.mimer.no. 4 A 213.184.200.111
name3.mimer.no. 4 A 51.13.68.251
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0