Apex domains cannot have CNAME records.
Question and response
Question
dig ns3.svenskadomaner.se. NS
Answer
ns3.svenskadomaner.se. 5 NS ns2.domain99.com.
ns3.svenskadomaner.se. 5 NS ns1.domain99.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0