Apex domains cannot have CNAME records.
Question and response
Question
dig split-dedicated.com. NS
Answer
split-dedicated.com. 1 NS ns1.crucialwebhost.com.
split-dedicated.com. 1 NS ns3.crucialwebhost.com.
split-dedicated.com. 1 NS ns2.crucialwebhost.com.
Authority
The response has no authority records.
Additional
ns1.crucialwebhost.com. 1 A 198.91.30.43
ns2.crucialwebhost.com. 1 A 64.38.231.139
ns3.crucialwebhost.com. 1 A 198.91.30.43
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0