80.ry.cz has no CNAME records.
Question and response
Question
dig 80.ry.cz. NS
Answer
The response has no answer records.
Authority
ry.cz. 1800 SOA ns.gransy.com. root.gransy.com. 2753303420 86400 900 1209600 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0