Apex domains cannot have CNAME records.
Question and response
Question
dig spf.hosting-pf.net. NS
Answer
spf.hosting-pf.net. 5 NS ns-spf2.hosting-pf.net.
spf.hosting-pf.net. 5 NS ns-spf.hosting-pf.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0