Apex domains cannot have CNAME records.
Question and response
Question
dig chalmers.se. NS
Answer
chalmers.se. 5 NS ns2.chalmers.se.
chalmers.se. 5 NS ns1.chalmers.se.
chalmers.se. 5 NS sunic.sunet.se.
chalmers.se. 5 NS ns3.chalmers.se.
Authority
The response has no authority records.
Additional
ns1.chalmers.se. 5 A 129.16.2.40
ns2.chalmers.se. 5 A 129.16.253.252
ns3.chalmers.se. 5 A 192.36.120.11
sunic.sunet.se. 5 A 192.36.125.2
ns1.chalmers.se. 5 AAAA 2001:6b0:2:10:0:0:0:1
ns2.chalmers.se. 5 AAAA 2001:6b0:2:20:0:0:0:1
ns3.chalmers.se. 5 AAAA 2001:2040:63:0:0:0:0:11
sunic.sunet.se. 5 AAAA 2001:6b0:7:0:0:0:0:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0