pluto2.gtsgroup.cz has no CNAME records.
Question and response
Question
dig pluto2.gtsgroup.cz. NS
Answer
The response has no answer records.
Authority
gtsgroup.cz. 9913 SOA server1.gts.cz. hostmaster.cz.net. 2024050200 28800 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0