Apex domains cannot have CNAME records.
Question and response
Question
dig esvalabs.com. NS
Answer
esvalabs.com. 5 NS ns-1608.awsdns-09.co.uk.
esvalabs.com. 5 NS ns-817.awsdns-38.net.
esvalabs.com. 5 NS ns-187.awsdns-23.com.
esvalabs.com. 5 NS ns-1191.awsdns-20.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0