Apex domains cannot have CNAME records.
Question and response
Question
dig 50-56-72-228.static.cloud-ips.com. NS
Answer
50-56-72-228.static.cloud-ips.com. 5 NS nsg2.namebrightdns.com.
50-56-72-228.static.cloud-ips.com. 5 NS nsg1.namebrightdns.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0