Apex domains cannot have CNAME records.
Question and response
Question
dig instance.cloud.sunet.se. NS
Answer
instance.cloud.sunet.se. 5 NS ns1.safedc.net.
instance.cloud.sunet.se. 5 NS ns2.safedc.net.
instance.cloud.sunet.se. 5 NS ns3.safedc.net.
instance.cloud.sunet.se. 5 NS ns4.safedc.net.
Authority
The response has no authority records.
Additional
ns1.safedc.net. 4 A 194.58.192.50
ns2.safedc.net. 4 A 194.58.198.50
ns3.safedc.net. 4 A 185.42.137.103
ns4.safedc.net. 4 A 63.34.32.172
ns1.safedc.net. 4 AAAA 2a01:3f1:50:0:0:0:0:53
ns2.safedc.net. 4 AAAA 2a01:3f1:3050:0:0:0:0:53
ns3.safedc.net. 4 AAAA 2a01:3f0:400:0:0:0:0:50
ns4.safedc.net. 4 AAAA 2a05:d018:184:4853:0:0:0:53
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0