Apex domains cannot have CNAME records.
Question and response
Question
dig extreme-central.com. NS
Answer
extreme-central.com. 5 NS ns-122.awsdns-15.com.
extreme-central.com. 5 NS ns-622.awsdns-13.net.
extreme-central.com. 5 NS ns-1072.awsdns-06.org.
extreme-central.com. 5 NS ns-1922.awsdns-48.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0