Apex domains cannot have CNAME records.
Question and response
Question
dig abacus.ch. NS
Answer
abacus.ch. 5 NS dns1-2.abainfra.net.
abacus.ch. 5 NS dns1-1.abainfra.net.
abacus.ch. 5 NS dns2-1.abainfra.net.
abacus.ch. 5 NS dns1-3.abainfra.net.
Authority
The response has no authority records.
Additional
dns1-1.abainfra.net. 5 A 46.227.228.101
dns1-2.abainfra.net. 5 A 46.227.226.107
dns1-3.abainfra.net. 5 A 91.92.201.166
dns2-1.abainfra.net. 5 A 46.227.228.122
dns1-1.abainfra.net. 5 AAAA 2a02:cd8:2ee3:e400:0:0:0:77
dns1-2.abainfra.net. 5 AAAA 2a02:cd8:2ee3:e200:0:0:0:6a
dns1-3.abainfra.net. 5 AAAA 2a04:c43:e00:258a:446:b8ff:fe00:15b5
dns2-1.abainfra.net. 5 AAAA 2a02:cd8:2ee3:e400:0:0:0:69
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0