Apex domains cannot have CNAME records.
Question and response
Question
dig voyager.pl. NS
Answer
voyager.pl. 5 NS ns2.he.net.
voyager.pl. 5 NS ns3.voyager.pl.
voyager.pl. 5 NS ns3.he.net.
voyager.pl. 5 NS ns5.voyager.pl.
Authority
The response has no authority records.
Additional
ns2.he.net. 5 A 216.218.131.2
ns3.he.net. 5 A 216.218.132.2
ns3.voyager.pl. 5 A 77.65.151.4
ns5.voyager.pl. 5 A 51.38.133.126
ns2.he.net. 5 AAAA 2001:470:200:0:0:0:0:2
ns3.he.net. 5 AAAA 2001:470:300:0:0:0:0:2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0