_spf.network.cz has no CNAME records.
Question and response
Question
dig _spf.network.cz. NS
Answer
The response has no answer records.
Authority
network.cz. 8400 SOA trubka.network.cz. ondrej.filip.info. 2024022709 3600 600 1814400 8400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0