Apex domains cannot have CNAME records.
Question and response
Question
dig payrexx.com. NS
Answer
payrexx.com. 5 NS ns-1721.awsdns-23.co.uk.
payrexx.com. 5 NS ns-1457.awsdns-54.org.
payrexx.com. 5 NS ns-199.awsdns-24.com.
payrexx.com. 5 NS ns-620.awsdns-13.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0