Apex domains cannot have CNAME records.
Question and response
Question
dig klfree.net. NS
Answer
klfree.net. 5 NS ns1.klfree.cz.
klfree.net. 5 NS ns2.klfree.cz.
klfree.net. 5 NS charon.hkfree.org.
Authority
The response has no authority records.
Additional
ns1.klfree.cz. 5 A 81.201.48.46
ns2.klfree.cz. 5 A 81.201.48.45
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0