Apex domains cannot have CNAME records.
Question and response
Question
dig compugroup.com. NS
Answer
compugroup.com. 4 NS dns1.teliko.net.
compugroup.com. 4 NS dns2.teliko.net.
Authority
The response has no authority records.
Additional
dns1.teliko.net. 1 A 217.17.16.162
dns2.teliko.net. 1 A 217.17.28.162
dns1.teliko.net. 1 AAAA 2a01:5580:fffd:34:0:0:0:114
dns2.teliko.net. 1 AAAA 2a01:5580:fffd:30:0:0:0:98
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0