Apex domains cannot have CNAME records.
Question and response
Question
dig plugcrm.net. NS
Answer
plugcrm.net. 5 NS ns-1834.awsdns-37.co.uk.
plugcrm.net. 5 NS ns-1081.awsdns-07.org.
plugcrm.net. 5 NS ns-227.awsdns-28.com.
plugcrm.net. 5 NS ns-603.awsdns-11.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0