Apex domains cannot have CNAME records.
Question and response
Question
dig pulsen.se. NS
Answer
pulsen.se. 5 NS ns1.pulsen.se.
pulsen.se. 5 NS ns2.pulsen.se.
pulsen.se. 5 NS ns3.pulsen.se.
Authority
The response has no authority records.
Additional
ns1.pulsen.se. 5 A 194.132.117.134
ns2.pulsen.se. 5 A 194.132.117.135
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0