Apex domains cannot have CNAME records.
Question and response
Question
dig sbfeltedfibers.com. NS
Answer
sbfeltedfibers.com. 5 NS ns-1638.awsdns-12.co.uk.
sbfeltedfibers.com. 5 NS ns-983.awsdns-58.net.
sbfeltedfibers.com. 5 NS ns-1092.awsdns-08.org.
sbfeltedfibers.com. 5 NS ns-1178.awsdns-19.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0