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 2kn8puv5k1vjecmtj5hg14bl3f6puon5.dbk.dk is not the root of its zone.
Instead, try zone transfer on dbk.dk .
Instead, try zone transfer on dbk.dk .