Apex domains cannot have CNAME records.
Question and response
Question
dig sipit.be. NS
Answer
sipit.be. 5 NS ns9.zoneedit.com.
sipit.be. 5 NS ns13.zoneedit.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0