_spf.grapesc.cz has no CNAME records.
Question and response
Question
dig _spf.grapesc.cz. NS
Answer
The response has no answer records.
Authority
grapesc.cz. 600 SOA ns1.grapesc.cz. domeny.grapesc.cz. 2025501073 10800 7200 1209600 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0