Apex domains cannot have CNAME records.
Question and response
Question
dig it-optics.com. NS
Answer
it-optics.com. 4 NS dns5.it-optics.com.
it-optics.com. 4 NS dns6.it-optics.com.
Authority
The response has no authority records.
Additional
dns5.it-optics.com. 4 A 178.32.40.191
dns6.it-optics.com. 4 A 84.46.245.160
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0