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 21ihv0s1r6sngi46imgt0s4cgbc2e0vv.itfhosting.dk is not the root of its zone.
Instead, try zone transfer on itfhosting.dk .
Instead, try zone transfer on itfhosting.dk .