Apex domains cannot have CNAME records.
Question and response
Question
dig telia.se. NS
Answer
telia.se. 5 NS dns.telia.se.
telia.se. 5 NS dns1.telia.se.
telia.se. 5 NS sehby01dns.telia.se.
Authority
The response has no authority records.
Additional
dns.telia.se. 5 A 193.44.165.16
dns1.telia.se. 5 A 81.236.34.35
sehby01dns.telia.se. 5 A 193.44.164.165
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0