Apex domains cannot have CNAME records.
Question and response
Question
dig mailrcloud.com. NS
Answer
mailrcloud.com. 5 NS aron.ns.cloudflare.com.
mailrcloud.com. 5 NS cody.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0