Apex domains cannot have CNAME records.
Question and response
Question
dig ac-net.se. NS
Answer
ac-net.se. 5 NS global.excedodns.com.
ac-net.se. 5 NS emea.excedodns.eu.
ac-net.se. 5 NS sto.excedodns.se.
ac-net.se. 5 NS world.excedodns.org.
ac-net.se. 5 NS nordic.excedodns.net.
Authority
The response has no authority records.
Additional
sto.excedodns.se. 5 A 185.42.137.101
emea.excedodns.eu. 5 A 194.58.192.48
world.excedodns.org. 5 A 162.219.54.130
global.excedodns.com. 5 A 194.58.198.48
nordic.excedodns.net. 5 A 162.219.55.130
sto.excedodns.se. 5 AAAA 2a01:3f0:400:0:0:0:0:48
emea.excedodns.eu. 5 AAAA 2a01:3f1:48:0:0:0:0:53
world.excedodns.org. 5 AAAA 2620:10a:80eb:0:0:0:0:42
global.excedodns.com. 5 AAAA 2a01:3f1:3048:0:0:0:0:53
nordic.excedodns.net. 5 AAAA 2620:10a:80ec:0:0:0:0:42
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0