Apex domains cannot have CNAME records.
Question and response
Question
dig itsystemsplus.com. NS
Answer
itsystemsplus.com. 5 NS ns-1305.awsdns-35.org.
itsystemsplus.com. 5 NS ns-1034.awsdns-01.org.
itsystemsplus.com. 5 NS ns-1245.awsdns-27.org.
itsystemsplus.com. 5 NS ns-1634.awsdns-12.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0