mail.interkar.pl has no CNAME records.
Question and response
Question
dig mail.interkar.pl. NS
Answer
The response has no answer records.
Authority
interkar.pl. 8857 SOA ns1.interkar.pl. hostmaster.interkar.pl. 2011092501 1200 400 2419200 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0