Apex domains cannot have CNAME records.
Question and response
Question
dig 3s.pl. NS
Answer
3s.pl. 5 NS ns1.3s.pl.
3s.pl. 5 NS ns2.3s.pl.
Authority
The response has no authority records.
Additional
ns1.3s.pl. 5 A 85.14.85.14
ns2.3s.pl. 5 A 85.14.85.2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0