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 8cdh1au09o7fg6q7bi3sgo9640otuh2d.letsvisualize.dk is not the root of its zone.
Instead, try zone transfer on letsvisualize.dk .
Instead, try zone transfer on letsvisualize.dk .