Apex domains cannot have CNAME records.
Question and response
Question
dig gubermanmd.com. NS
Answer
gubermanmd.com. 5 NS ns-659.awsdns-18.net.
gubermanmd.com. 5 NS ns-1381.awsdns-44.org.
gubermanmd.com. 5 NS ns-342.awsdns-42.com.
gubermanmd.com. 5 NS ns-437.awsdns-54.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0