Apex domains cannot have CNAME records.
Question and response
Question
dig crystone.se. NS
Answer
crystone.se. 4 NS ns2.loopiagroup.com.
crystone.se. 4 NS ns1.loopiagroup.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0