spx01.mail.isx.net.nz IXFR zone transfer

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 spx01.mail.isx.net.nz is not the root of its zone.
Instead, try zone transfer on isx.net.nz .