Apex domains cannot have CNAME records.
Question and response
Question
dig katapultdns.com. NS
Answer
katapultdns.com. 5 NS ns1.katapultdns.com.
katapultdns.com. 5 NS ns2.katapultdns.com.
Authority
The response has no authority records.
Additional
ns1.katapultdns.com. 5 A 151.252.1.100
ns2.katapultdns.com. 5 A 151.252.2.100
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0