Apex domains cannot have CNAME records.
Question and response
Question
dig store1rpc.com. NS
Answer
store1rpc.com. 4 NS pns71.cloudns.net.
store1rpc.com. 4 NS ns73.cloudns.com.
store1rpc.com. 4 NS ns72.cloudns.net.
store1rpc.com. 4 NS ns74.cloudns.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0