Apex domains cannot have CNAME records.
Question and response
Question
dig hotel-vertical.com. NS
Answer
hotel-vertical.com. 5 NS ns-390.awsdns-48.com.
hotel-vertical.com. 5 NS ns-1814.awsdns-34.co.uk.
hotel-vertical.com. 5 NS ns-1335.awsdns-38.org.
hotel-vertical.com. 5 NS ns-706.awsdns-24.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0