Apex domains cannot have CNAME records.
Question and response
Question
dig tec4u-solutions.com. NS
Answer
tec4u-solutions.com. 5 NS ns2.internet1.de.
tec4u-solutions.com. 5 NS ns.internet1.de.
tec4u-solutions.com. 5 NS ns3.internet1.de.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0