Apex domains cannot have CNAME records.
Question and response
Question
dig cltel.net. NS
Answer
cltel.net. 4 NS ns2.ispn.net.
cltel.net. 4 NS ns1.ispn.net.
Authority
The response has no authority records.
Additional
ns1.ispn.net. 4 A 64.35.208.1
ns2.ispn.net. 4 A 64.35.214.1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0