Apex domains cannot have CNAME records.
Question and response
Question
dig mtsbondindex.com. NS
Answer
mtsbondindex.com. 4 NS ns-936.awsdns-53.net.
mtsbondindex.com. 4 NS ns-2016.awsdns-60.co.uk.
mtsbondindex.com. 4 NS ns-561.awsdns-06.net.
mtsbondindex.com. 4 NS ns-1725.awsdns-23.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0