Apex domains cannot have CNAME records.
Question and response
Question
dig seismic.com. NS
Answer
seismic.com. 5 NS ns-611.awsdns-12.net.
seismic.com. 5 NS ns-460.awsdns-57.com.
seismic.com. 5 NS ns-1829.awsdns-36.co.uk.
seismic.com. 5 NS ns-1254.awsdns-28.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0