Apex domains cannot have CNAME records.
Question and response
Question
dig sveanet.se. NS
Answer
sveanet.se. 3 NS ns-1599.awsdns-07.co.uk.
sveanet.se. 3 NS ns-1157.awsdns-16.org.
sveanet.se. 3 NS ns-182.awsdns-22.com.
sveanet.se. 3 NS ns-815.awsdns-37.net.
Authority
The response has no authority records.
Additional
ns-182.awsdns-22.com. 4 A 205.251.192.182
ns-815.awsdns-37.net. 4 A 205.251.195.47
ns-1157.awsdns-16.org. 4 A 205.251.196.133
ns-1599.awsdns-07.co.uk. 4 A 205.251.198.63
ns-182.awsdns-22.com. 4 AAAA 2600:9000:5300:b600:0:0:0:1
ns-815.awsdns-37.net. 4 AAAA 2600:9000:5303:2f00:0:0:0:1
ns-1157.awsdns-16.org. 4 AAAA 2600:9000:5304:8500:0:0:0:1
ns-1599.awsdns-07.co.uk. 4 AAAA 2600:9000:5306:3f00:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0