Apex domains cannot have CNAME records.
Question and response
Question
dig postandcourrier.com. NS
Answer
postandcourrier.com. 4 NS ns-1288.awsdns-33.org.
postandcourrier.com. 4 NS ns-1969.awsdns-54.co.uk.
postandcourrier.com. 4 NS ns-591.awsdns-09.net.
postandcourrier.com. 4 NS ns-1196.awsdns-21.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0