Apex domains cannot have CNAME records.
Question and response
Question
dig smtowm.com. NS
Answer
smtowm.com. 5 NS ns-1590.awsdns-06.co.uk.
smtowm.com. 5 NS ns-1037.awsdns-01.org.
smtowm.com. 5 NS ns-120.awsdns-15.com.
smtowm.com. 5 NS ns-1783.awsdns-30.co.uk.
Authority
The response has no authority records.
Additional
ns-1783.awsdns-30.co.uk. 4 A 205.251.198.247
ns-1783.awsdns-30.co.uk. 4 AAAA 2600:9000:5306:f700:0:0:0:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0