Apex domains cannot have CNAME records.
Question and response
Question
dig nsc1.raxhosting.com. NS
Answer
nsc1.raxhosting.com. 5 NS ns1.raxhosting.com.
nsc1.raxhosting.com. 5 NS ns2.raxhosting.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0