Apex domains cannot have CNAME records.
Question and response
Question
dig telenor.se. NS
Answer
telenor.se. 5 NS dns2.telenor.se.
telenor.se. 5 NS nordic1.dnsnode.net.
telenor.se. 5 NS nsu.dnsnode.net.
telenor.se. 5 NS nsp.dnsnode.net.
telenor.se. 5 NS dns1.telenor.se.
telenor.se. 5 NS dns3.telenor.se.
Authority
The response has no authority records.
Additional
dns1.telenor.se. 5 A 213.150.135.213
dns2.telenor.se. 5 A 213.150.128.30
dns3.telenor.se. 5 A 62.127.3.139
dns1.telenor.se. 5 AAAA 2a02:1400:17:101:0:0:0:1
dns2.telenor.se. 5 AAAA 2a02:1400:17:102:0:0:0:1
dns3.telenor.se. 5 AAAA 2a02:1400:17:103:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0