Apex domains cannot have CNAME records.
Question and response
Question
dig flockgroups.com. NS
Answer
flockgroups.com. 5 NS ns-45.awsdns-05.com.
flockgroups.com. 5 NS ns-604.awsdns-11.net.
flockgroups.com. 5 NS ns-1134.awsdns-13.org.
flockgroups.com. 5 NS ns-1704.awsdns-21.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0