Apex domains cannot have CNAME records.
Question and response
Question
dig agentspam.com. NS
Answer
agentspam.com. 1 NS ns.cyberlynk.net.
agentspam.com. 1 NS ns0.cyberlynk.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0