Apex domains cannot have CNAME records.
Question and response
Question
dig frockcloud.com. NS
Answer
frockcloud.com. 5 NS ns2.frockcloud.com.
frockcloud.com. 5 NS ns1.frockcloud.com.
Authority
The response has no authority records.
Additional
ns1.frockcloud.com. 5 A 94.75.214.95
ns2.frockcloud.com. 5 A 51.38.79.149
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0