Apex domains cannot have CNAME records.
Question and response
Question
dig mail.kommosrv.com. NS
Answer
mail.kommosrv.com. 3 NS ns4.kommosrv.com.
mail.kommosrv.com. 3 NS ns3.kommosrv.com.
Authority
The response has no authority records.
Additional
ns3.kommosrv.com. 3 A 204.74.253.222
ns4.kommosrv.com. 3 A 169.150.216.250
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0