Apex domains cannot have CNAME records.
Question and response
Question
dig ipartners.pl. NS
Answer
ipartners.pl. 5 NS ns2.ikp.pl.
ipartners.pl. 5 NS ns4.ikp.pl.
ipartners.pl. 5 NS ns1.ikp.pl.
Authority
The response has no authority records.
Additional
ns1.ikp.pl. 5 A 157.25.5.2
ns2.ikp.pl. 5 A 217.153.128.156
ns4.ikp.pl. 5 A 217.8.168.245
ns1.ikp.pl. 5 AAAA 2001:4190:8002:1:0:0:0:302
ns2.ikp.pl. 5 AAAA 2001:4190:8002:1:0:0:0:2
ns4.ikp.pl. 5 AAAA 2001:4190:8002:8001:0:0:0:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0