RDAP source
https://rdap.nic.cz
port 43: whois.nic.cz
The registry blocks changes to the domain.
The registry blocks transfers. Often set for valuable or disputed domains.
Signed delegation in place.
WHOIS source
whois.nic.cz
REG-INTERNET-CZ REG-WEBGLOBE REG-WEBGLOBE
INTERNET CZ, a.s.
Make a direct request at ICANN.