Apex domains cannot have CNAME records.
Question and response
Question
dig miljodata.se. NS
Answer
miljodata.se. 4 NS nic2.adato.se.
miljodata.se. 4 NS e.ns.buddyns.com.
miljodata.se. 4 NS b.ns.buddyns.com.
miljodata.se. 4 NS c.ns.buddyns.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0