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 974mg4a9vj6nv2pnavq5nvsk7frrjs34.mailcloud.dk is not the root of its zone.
Instead, try zone transfer on mailcloud.dk .
Instead, try zone transfer on mailcloud.dk .