Apex domains cannot have CNAME records.
Question and response
Question
dig hem.net. NS
Answer
hem.net. 5 NS dns1.hem.net.
hem.net. 5 NS dns2.hem.net.
Authority
The response has no authority records.
Additional
dns1.hem.net. 5 A 44.5.25.70
dns2.hem.net. 5 A 44.5.25.73
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0