Apex domains cannot have CNAME records.
Question and response
Question
dig cartsguru.io. NS
Answer
cartsguru.io. 5 NS ns-738.awsdns-28.net.
cartsguru.io. 5 NS ns-1503.awsdns-59.org.
cartsguru.io. 5 NS ns-1639.awsdns-12.co.uk.
cartsguru.io. 5 NS ns-461.awsdns-57.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0