Apex domains cannot have CNAME records.
Question and response
Question
dig axone.ch. NS
Answer
axone.ch. 5 NS hk21.irondns.net.
axone.ch. 5 NS us19-east.irondns.net.
axone.ch. 5 NS us20-west.irondns.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0