ns.bcom.cz has no CNAME records.
Question and response
Question
dig ns.bcom.cz. NS
Answer
The response has no answer records.
Authority
bcom.cz. 900 SOA ns.webx.cz. hostmaster.webx.cz. 2026021402 10800 1800 1209600 7200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0