Apex domains cannot have CNAME records.
Question and response
Question
dig mansfieldrealestateagent.com. NS
Answer
mansfieldrealestateagent.com. 5 NS ns1.mansfieldrealestateagent.com.
mansfieldrealestateagent.com. 5 NS ns2.mansfieldrealestateagent.com.
Authority
The response has no authority records.
Additional
ns1.mansfieldrealestateagent.com. 5 A 23.137.139.22
ns2.mansfieldrealestateagent.com. 5 A 23.137.139.26
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0