Apex domains cannot have CNAME records.
Question and response
Question
dig plemtyoffish.com. NS
Answer
plemtyoffish.com. 5 NS ns-1749.awsdns-26.co.uk.
plemtyoffish.com. 5 NS ns-1611.awsdns-09.co.uk.
plemtyoffish.com. 5 NS ns-1069.awsdns-05.org.
plemtyoffish.com. 5 NS ns-1997.awsdns-57.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0