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 sn3jicg9jnha5v4tmn2c8ah1r8rd4h4e.smtp.dk is not the root of its zone.
Instead, try zone transfer on smtp.dk .
Instead, try zone transfer on smtp.dk .