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 dkim-k2._domainkey.netnavi.cloud. is not the root of its zone.
Instead, try zone transfer on willischan-co-uk.dk.mxthunder.net .
Instead, try zone transfer on willischan-co-uk.dk.mxthunder.net .