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 tubrmjbn0ava4f5bsgs2ecdokkbi7l06.mailcloud.dk is not the root of its zone.
Instead, try zone transfer on mailcloud.dk .
Instead, try zone transfer on mailcloud.dk .