Apex domains cannot have CNAME records.
Question and response
Question
dig mozartsystems.org. NS
Answer
mozartsystems.org. 3 NS ns-272.awsdns-34.com.
mozartsystems.org. 3 NS ns-319.awsdns-39.com.
mozartsystems.org. 3 NS ns-1036.awsdns-01.org.
mozartsystems.org. 3 NS ns-1147.awsdns-15.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0