Apex domains cannot have CNAME records.
Question and response
Question
dig nis.telia.net. NS
Answer
nis.telia.net. 5 NS dns2.telia.com.
nis.telia.net. 5 NS dns358.fi.telia.net.
nis.telia.net. 5 NS dns1.telia.com.
nis.telia.net. 5 NS dns49.de.telia.net.
Authority
The response has no authority records.
Additional
dns1.telia.com. 5 A 81.228.11.67
dns2.telia.com. 5 A 81.228.10.67
dns49.de.telia.net. 5 A 213.248.77.82
dns358.fi.telia.net. 5 A 88.194.40.67
dns1.telia.com. 5 AAAA 2001:2040:c001:101:0:0:0:5
dns2.telia.com. 5 AAAA 2001:2040:c001:401:0:0:0:6
dns49.de.telia.net. 5 AAAA 2001:2030:c000:5:0:0:0:4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0