Apex domains cannot have CNAME records.
Question and response
Question
dig antibiotic500mg-flagyl.org. NS
Answer
antibiotic500mg-flagyl.org. 5 NS ns-1411.awsdns-48.org.
antibiotic500mg-flagyl.org. 5 NS ns-1165.awsdns-17.org.
antibiotic500mg-flagyl.org. 5 NS ns-722.awsdns-26.net.
antibiotic500mg-flagyl.org. 5 NS ns-2027.awsdns-61.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0