Apex domains cannot have CNAME records.
Question and response
Question
dig sadleroptical.com. NS
Answer
sadleroptical.com. 5 NS ns-1260.awsdns-29.org.
sadleroptical.com. 5 NS ns-1264.awsdns-30.org.
sadleroptical.com. 5 NS ns-1396.awsdns-46.org.
sadleroptical.com. 5 NS ns-862.awsdns-43.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0