Apex domains cannot have CNAME records.
Question and response
Question
dig se.telenor.net. NS
Answer
se.telenor.net. 3 NS ns3.se.telenor.net.
se.telenor.net. 3 NS ns1.se.telenor.net.
se.telenor.net. 3 NS ns2.se.telenor.net.
Authority
The response has no authority records.
Additional
ns1.se.telenor.net. 3 A 195.54.122.193
ns2.se.telenor.net. 3 A 195.54.122.194
ns3.se.telenor.net. 3 A 81.26.229.2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0