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 20toib09v97kg6i5o57b8o66b152vd50.dnsfactory.dk is not the root of its zone.
Instead, try zone transfer on dnsfactory.dk .
Instead, try zone transfer on dnsfactory.dk .