Changes since SOA version
IXFR is a zone transfer request that returns changes since a specific SOA version. Enter the SOA version to request changes since then.
Not an apex domain
The domain 5-104-16-0.members.slavicin.unart.cz is not the root of its zone.
Instead, try zone transfer on members.slavicin.unart.cz .
Instead, try zone transfer on members.slavicin.unart.cz .