Apex domains cannot have CNAME records.
Question and response
Question
dig sinegra100mg.com. NS
Answer
sinegra100mg.com. 1 NS ns-296.awsdns-37.com.
sinegra100mg.com. 1 NS ns-1648.awsdns-14.co.uk.
sinegra100mg.com. 1 NS ns-1050.awsdns-03.org.
sinegra100mg.com. 1 NS ns-476.awsdns-59.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0