Apex domains cannot have CNAME records.
Question and response
Question
dig heatingcoolingsanitarysystems.com. NS
Answer
heatingcoolingsanitarysystems.com. 5 NS ns1.heatingcoolingsanitarysystems.com.
heatingcoolingsanitarysystems.com. 5 NS ns2.heatingcoolingsanitarysystems.com.
Authority
The response has no authority records.
Additional
ns1.heatingcoolingsanitarysystems.com. 5 A 64.62.133.90
ns2.heatingcoolingsanitarysystems.com. 5 A 64.62.133.93
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0