Apex domains cannot have CNAME records.
Question and response
Question
dig spnet.net. NS
Answer
spnet.net. 5 NS purgatory.spnet.net.
spnet.net. 5 NS ns.spnet.net.
Authority
The response has no authority records.
Additional
ns.spnet.net. 5 A 212.50.0.10
purgatory.spnet.net. 5 A 212.50.0.15
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0