Apex domains cannot have CNAME records.
Question and response
Question
dig pricetravel.com.mx. NS
Answer
pricetravel.com.mx. 5 NS ns-416.awsdns-52.com.
pricetravel.com.mx. 5 NS ns-1995.awsdns-57.co.uk.
pricetravel.com.mx. 5 NS ns-1188.awsdns-20.org.
pricetravel.com.mx. 5 NS ns-976.awsdns-58.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0