Apex domains cannot have CNAME records.
Question and response
Question
dig cention.com. NS
Answer
cention.com. 1 NS ns-325.awsdns-40.com.
cention.com. 1 NS ns-1115.awsdns-11.org.
cention.com. 1 NS ns-996.awsdns-60.net.
cention.com. 1 NS ns-1883.awsdns-43.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0